ทำ CheckBox ใน DataGridView เพื่อให้ Saveได้หลาย Record พอเลือกบาง Record ทำไมมันไม่ Save อันสุดท้ายที่เลือกค่ะ VB.NET (Win App)

 Private Sub frmTestCheckBox_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Showdatas()
    End Sub
    Private Sub Showdatas()
        Conn = New SqlConnection
        OpenConn()

        Sb.Remove(0, Sb.Length)
        Sb.Append("SELECT M_WorkDate,M_ShiftCode,M_ShiftDes,M_TimeIn,M_TimeOut,M_Rate,OT_TypeName,M_SumOT,M_SumSys,M_OTCorrect,M_Status,M_CorrectedUser,M_CorrectedDate,M_EmpCode from V_OTMaster2 ")
        Sb.Append(" WHERE M_EmpCode ='4001085'")
        Sb.Append(" and M_WorkDate  between '08/01/2011' and '08/31/2011'")
        'Sb.Append(" and M_Status <> 'A'")
        Sb.Append(" order by M_EmpCode,M_WorkDate,M_Rate ")
        Dim sqlShift As String
        sqlShift = Sb.ToString()
        Comm = New SqlCommand
        With Comm
            .CommandText = sqlShift
            .CommandType = CommandType.Text
            .Connection = Conn
            dr = .ExecuteReader()
            If dr.HasRows Then
                Dim dtExtshift As DataTable
                dtExtshift = New DataTable
                dtExtshift.Load(dr)
                dtgOvertime.DataSource = dtExtshift
                FormatDgvOvertime()
            Else
                dtgOvertime.DataSource = Nothing
            End If
        End With

    End Sub
    Private Sub FormatDgvOvertime()
        With dtgOvertime
            If .RowCount > 0 Then
                Me.dtgOvertime.Columns.Clear()

                With dtgOvertime.ColumnHeadersDefaultCellStyle
                    .BackColor = Color.Navy
                    .ForeColor = Color.White
                End With

                Dim ColumnTextBox As DataGridViewTextBoxColumn

                '*** Column (Select) ***'
                Dim ColumnCheckBox As New DataGridViewCheckBoxColumn()
                ColumnCheckBox.Width = 30
                ColumnCheckBox.DataPropertyName = "Select"
                Me.dtgOvertime.Columns.Add(ColumnCheckBox)


                dtgOvertime.Columns(0).Frozen = False

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_WorkDate"
                ColumnTextBox.HeaderText = "Work Date"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_ShiftCode"
                ColumnTextBox.HeaderText = "Shift Code"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_ShiftDes"
                ColumnTextBox.HeaderText = "Shift Description"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_TimeIn"
                ColumnTextBox.HeaderText = "Time In"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_TimeOut"
                ColumnTextBox.HeaderText = "Time Out"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_Rate"
                ColumnTextBox.HeaderText = "Rate"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "OT_TypeName"
                ColumnTextBox.HeaderText = "OT TypeName"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_SumOT"
                ColumnTextBox.HeaderText = "SumOT"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_SumSys"
                ColumnTextBox.HeaderText = "SumSys"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_OTCorrect"
                ColumnTextBox.HeaderText = "OT Correct"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_Status"
                ColumnTextBox.HeaderText = "Status"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_CorrectedUser"
                ColumnTextBox.HeaderText = "CorrectedUser"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_CorrectedDate"
                ColumnTextBox.HeaderText = "CorrectedDate"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)

                ColumnTextBox = New DataGridViewTextBoxColumn()
                ColumnTextBox.DataPropertyName = "M_EmpCode"
                ColumnTextBox.HeaderText = "EmpCode"
                ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
                ColumnTextBox.Width = 100
                Me.dtgOvertime.Columns.Add(ColumnTextBox)
                .Columns(14).Visible = False
            End If
        End With
    End Sub

 Conn = New SqlConnection
        OpenConn()
        For i As Integer = 0 To dtgOvertime.Rows.Count - 1
            Dim EmpCode As [String] = dtgOvertime.Rows(i).Cells(14).Value.ToString()
            Dim SumOT As [String] = dtgOvertime.Rows(i).Cells(9).Value.ToString()
            Dim WorkDate As [DateTime] = dtgOvertime.Rows(i).Cells(1).Value.ToString()
            Dim Rate As [String] = dtgOvertime.Rows(i).Cells(6).Value.ToString()
            Dim EmpCorrect As String = ConnString.UserID
            Dim chkCusID As Boolean
            chkCusID = New Boolean
            chkCusID = dtgOvertime.Rows(i).Cells(0).Value
            If chkCusID Then
                Tr = Conn.BeginTransaction()
                Sb.Remove(0, Sb.Length)
                Sb.Append("UPDATE Tb_OTMaster Set M_OTCorrect='" & SumOT & "', M_Status='C', M_CorrectedUser='" & EmpCorrect & "', M_CorrectedDate='" & Now.Date.ToString("M/d/yyyy") & "'")
                Sb.Append(" where M_EmpCode='" & EmpCode & "' And M_WorkDate='" & WorkDate.ToString("MM/dd/yyyy") & "' And M_Rate = '" & Rate & "'")
                Dim sqlAdd As String = ""
                sqlAdd = Sb.ToString()
                With Comm
                    .CommandText = sqlAdd
                    .CommandType = CommandType.Text
                    .Connection = Conn
                    .Transaction = Tr
                    .Parameters.Clear()
                    .ExecuteNonQuery()
                    Tr.Commit()
                End With
            End If
        Next
        Showdatas()