ถามนิดนึงครับ ผมคำนวณค่าในฐานข้อมูล Access แล้วค่าที่ได้เป็น Null ทั้ง ๆ ที่ในนั้นมี ข้อมูล

 Private Sub SumSaleDay1()
        Dim dt As New DataTable
        Dim ds As New DataSet
        Dim strSQL, strSQL1, strqr As String
        Dim icount As Double
        Dim strConn As String = "Provider = Microsoft.Jet.OLEDB.4.0;Data Source = C:\Documents and Settings\akasit\Desktop\New.mdb"
        Dim ConnDB As OleDb.OleDbConnection = New OleDb.OleDbConnection(strConn)
        ConnDB.Open()
        icount = 0
        strSQL = "SELECT * FROM ReportSL"
        adp = New OleDbDataAdapter(strSQL, ConnDB)
        adp.Fill(ds)
        dt = ds.Tables(0)
        If dt.Rows.Count >= 0 Then
            For i As Byte = 0 To dt.Rows.Count - 1
                strsqr = "SELECT sum (TRD_B_SELL) FROM Newdata WHERE SLMN_CODE like '" & dt.Rows(i)("IdEmp") & "' and DI_DATE Like '" & Me.Label1.Text & "' and DT_PROPERTIES Like '307' and AR_CODE Not Like 'E1C0014017' and TRD_SH_CODE Like '885*'"
                'Command = New OleDbCommand(strsqr, ConnDB)
                Command = New System.Data.OleDb.OleDbCommand(strsqr, ConnDB)
                Try
                    Me.Label8.Text = Command.ExecuteScalar(strsqr)
                    'icount.ToString("n2")
                    'Me.Label8.Text = icount
                Catch ex As Exception
                    Label8.Text = "0"
                End Try
                strqr = "UPDATE ReportSL SET SaleDay = '" & Me.Label8.Text & "' WHERE IdEmp = '" & dt.Rows(i)("IdEmp") & "' "
                Command = New OleDbCommand(strqr, ConnDB)
                Command.ExecuteNonQuery()
            Next
        End If
ConnDB.Close()
    End Sub