ดู function นี้ให้หน่อยครับ มันไม่ทำงานไม่รู่ว่า ผิดตรงไหน ช่วยที่ครับ สำคัญมาก

Public Function isExist(ByVal barcode As String, ByVal d As String) As Boolean
        Dim dt As New DataTable
        Dim da As New OleDbDataAdapter(" SELECT tbl_DailyRecord.*, tbl_DailyRecord.Dates FROM tbl_DailyRecord WHERE tbl_DailyRecord.Dates > #" & d & " # AND tbl_DailyRecord.Dates < #" & d & " # AND  tbl_DailyRecord.LabourID = '" & CInt(barcode) & "' ", Conn)
        da.Fill(dt)
        If (dt.Rows.Count > 0) Then
            Return True
        Else
            Return False
        End If
    End Function

Private Sub btnOk_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOk.Click

        If txtLabourID.Text = "" Then
            MessageBox.Show("Please Check Barcode And Scan Again", "Scan Barcode", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtBarcode.Clear()
            txtBarcode.Focus()
            Exit Sub
        End If
        Dim barcode As String = txtLabourID.Text
        If txtBarcode.Text = "" Then
            MessageBox.Show("Please Scan Barcode", "Scan Barcode", MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtBarcode.Clear()
            txtBarcode.Focus()
        Else
            If isExist(barcode, dtpDateTime.Text) Then
                MessageBox.Show("You were already CheckIn to the System", "Already CheckIn", MessageBoxButtons.OK, MessageBoxIcon.Stop)
                txtBarcode.Clear()
                txtLabourID.Clear()
                txtFullnameEng.Clear()
                txtFullnameLao.Clear()
                txtAge.Clear()
                txtTimeIn.Clear()
                txtBarcode.Focus()
                'picLabour.Image = "No_Photo.bmp"
                If Not (picLabour.Image Is Nothing) Then
                    picLabour.Image.Dispose()
                    picLabour.Image = Nothing
                End If
            Else
                ' MessageBox.Show("Do You Want To Save ?", "Save", MessageBoxButtons.YesNo, MessageBoxIcon.Question)
                Try
                    sql = "insert into tbl_DailyRecord(LabourID,Nameeng,Dates,TimeIn,NSR,Species,Place,Description,Status)"
                    sql &= "values('" & txtLabourID.Text.Trim & "','" & txtFullnameEng.Text.Trim & "','" & dtpDateTime.Value.Date & "','" & dtpDateTime.Value & "',"
                    sql &= "" & CInt(cboNSR.SelectedValue) & "," & CInt(cboSpecies.SelectedValue) & ","
                    sql &= "" & CInt(cboPlace.SelectedValue) & "," & CInt(cboDescription.SelectedValue) & ","
                    sql &= "'I')"
                    Com = New OleDbCommand
                    With Com
                        .Connection = Conn
                        .CommandText = sql
                        .ExecuteNonQuery()
                    End With

                    'MessageBox.Show("Successful..!", "Result", MessageBoxButtons.OK, MessageBoxIcon.Information)

                    txtBarcode.Clear()
                    txtLabourID.Clear()
                    txtFullnameEng.Clear()
                    txtFullnameLao.Clear()
                    txtAge.Clear()
                    txtTimeIn.Clear()
                    txtBarcode.Focus()
                    'picLabour.Image = "No_Photo.bmp"
                    If Not (picLabour.Image Is Nothing) Then
                        picLabour.Image.Dispose()
                        picLabour.Image = Nothing
                    End If
                Catch ex As Exception
                    MessageBox.Show("Error. Because " & ex.Message, "Result", MessageBoxButtons.OK, MessageBoxIcon.Warning)
                End Try
            End If
        End If
    End Sub