主题：控制生产累计数不允许大于计划生产数

Select Case e.DataCol.name
    Case "本次生产数"
        If e.NewValue > 0 Then
            Dim dr As DataRow = DataTables("生产计划").Find("订单号='" & e.DataRow("订单号") & "' And 型号= '" & e.DataRow("产品名称") & "'")
            Dim dr1 As DataRow = DataTables("冲压车间工资表").Find("产品名称='"  & e.DataRow("产品名称") & "' And 生产工序= '" & e.DataRow("生产工序") & "'订单号='" & e.DataRow("订单号") & "'")
            Dim str1 As Double = dr1("累计生产数")
            Dim str2 As Double = dr1("未完工数")
            If dr IsNot Nothing Then
                Dim sum1 As Double = DataTables("生产计划").Compute("Sum(数量)","订单号='" & e.DataRow("订单号") & "' And 型号= '" & e.DataRow("产品名称") & "'")
                Dim sum As Double = e.DataTable.Compute("Sum(本次生产数)","订单号='" &  e.DataRow("订单号") & "' And 产品名称='" & e.DataRow("产品名称") & "' and 生产工序='" &  e.DataRow("生产工序") & "' and [_Identify] <> " & e.DataRow("_Identify"))
                dr1("累计生产数")= sum
                dr1("未完工数")= sum1- sum
                If sum + e.NewValue > sum1 Then
                    msgbox("数量超出!")
                    e.Cancel = True
                End If
            End If
        End If
End Select

我把这代码写到了冲压车间工资资表表事件里，但表体不显示数据，哪出问题了？