มันขึ้น Error แบบนี้ must declare the variable '@___'

Sub SaveItemHeader()
        '///////////////////////////////////////////////////
        Dim sb As New StringBuilder
        Dim com As New OleDbCommand

        Me.Cursor = Cursors.WaitCursor
        Try
            Me.ConnectDB()
            '///////////////////////////////////////////////////
            sb.Remove(0, sb.Length)
            sb.Append("INSERT INTO Buy(Code_Buy,Cat,Date1,Date2,Reason,Checks)")
            sb.Append(" VALUES (@CodeBuy,@Cat,@Date1,@Date2,@Reason,@Checks)")

            Dim sqlsave As String
            sqlsave = sb.ToString()

            With com
                .CommandText = sqlsave
                .Parameters.Clear()
                .Parameters.AddWithValue("@CodeBuy", OleDbType.VarChar).Value = Me.TextBox3.Text
                .Parameters.AddWithValue("@Cat", OleDbType.VarChar).Value = Me.ComboBox1.SelectedValue
                .Parameters.AddWithValue("@Date1", OleDbType.Date).Value = Me.DateTimePicker1.Value.Date
                .Parameters.AddWithValue("@Date2", OleDbType.Date).Value = Me.DateTimePicker2.Value.Date
                .Parameters.AddWithValue("@Reason", OleDbType.VarChar).Value = Val(Me.TextBox1.Text)
                .Parameters.AddWithValue("@Checks", OleDbType.VarChar).Value = Val(Me.TextBox2.Text)


                .CommandType = CommandType.Text
                .Connection = Conn
                .ExecuteNonQuery()
            End With

            Me.ClearItemDetial()
            Me.Cursor = Cursors.Default
        Catch ex As Exception
            MsgBox(ex.Message, MsgBoxStyle.Critical, "Error ไม่สามารถบันทึกข้อมูลได้")
            Exit Try
            Exit Sub
        Finally
            Me.Cursor = Cursors.Default
        End Try

    End Sub

Sub UpdateItem()
        '///////////////////////////////////////////////////
        Dim sb As New StringBuilder
        Dim com As New OleDbCommand
        Me.Cursor = Cursors.WaitCursor
        Try
            Me.ConnectDB()
            Dim sqlSave As String
            sqlSave = sb.ToString()
            '///////////////////////////////////////////////////
            sb.Remove(0, sb.Length)
            sb.Append("UPDATE Buy")
            sb.Append(" SET Cat=@Cat,")
            sb.Append(" Date1=@Date1,")
            sb.Append(" Date2=@Date2,")
            sb.Append(" Reason=@Reason,")
            sb.Append(" Checks=@Checks,")
            sb.Append(" Code_Buy=@CodeBuy,")


            sqlSave = sb.ToString()

            With com
                .CommandText = sqlSave
                .CommandType = CommandType.Text
                .Connection = Conn
                .Parameters.Clear()

                .Parameters.AddWithValue("@Cat", OleDbType.VarChar).Value = Me.ComboBox1.SelectedValue
                .Parameters.AddWithValue("@Date1", OleDbType.Date).Value = Format(Me.DateTimePicker1.Value, "dd/MM/yyyy")
                .Parameters.AddWithValue("@Reason", OleDbType.VarChar).Value = Val(Me.TextBox1.Text)
                .Parameters.AddWithValue("@Date2", OleDbType.Date).Value = Format(Me.DateTimePicker2.Value, "dd/MM/yyyy")
                .Parameters.AddWithValue("@Checks", OleDbType.VarChar).Value = Val(Me.TextBox2.Text)
                .Parameters.AddWithValue("@CodeBuy", OleDbType.VarChar).Value = Trim(Me.TextBox3.Text)


                .ExecuteNonQuery()
            End With
            Me.Cursor = Cursors.Default
            Me.ClearItemDetial()
            Me.Close()
        Catch ex As Exception
            MsgBox(ex.Message, MsgBoxStyle.Critical, "Error ไม่สามารถปรับปรุงรายการได้zzzzzzzzzzzz")
            Exit Try
            Exit Sub
        Finally
            Me.Cursor = Cursors.Default
        End Try
        
    End Sub