主题：[求助]解惑相同自动编号代码，表A行，表B不行

表A自动编号：

Select e.DataCol.Name
    Case "订单日期","类别"
        If e.DataRow.IsNull("订单日期") OrElse e.DataRow.IsNull("类别") Then
            e.DataRow("订单编号") = Nothing
        Else
            Dim d As Date = e.DataRow("订单日期")
            Dim y As Integer = d.Year
            Dim m As Integer = d.Month
            Dim Days As Integer = Date.DaysInMonth(y,m)
            Dim fd As Date = New Date(y,m,1) '获得该月的第一天
            Dim ld As Date = New Date(y,m,Days) '获得该月的最后一天
            Dim bh As String = e.DataRow("类别") & "-" & Format(d,"yyyyMM") & "-" '生成编号的前缀
            If e.DataRow("订单编号").StartsWith(bh) = False '如果单据编号前缀不符
                Dim max As String
                Dim idx As Integer
                Dim flt As String
                flt = "类别 = '"& e.DataRow("类别") & "' And 订单日期 >= #" & fd & "# And 订单日期 <= #" & ld & "# And [_Identify] <> " & e.DataRow("_Identify")
                max = e.DataTable.Compute("Max(订单编号)",flt) '取得该月的相同工程代码的最大单据编号
                If max > "" Then '如果存在最大单据编号
                    idx = CInt(max.Substring(12,4)) + 1 '获得最大单据编号的后四位顺序号,并加1
                Else
                    idx = 1 '否则顺序号等于1
                End If
                e.DataRow("订单编号") = bh & Format(idx,"0000")
            End If
        End If
End Select

表B自动编号：

Select e.DataCol.Name
    Case "销售日期","类别"
        If e.DataRow.IsNull("销售日期") OrElse e.DataRow.IsNull("类别") Then
            e.DataRow("销售编号") = Nothing
        Else
            Dim d As Date = e.DataRow("销售日期")
            Dim y As Integer = d.Year
            Dim m As Integer = d.Month
            Dim Days As Integer = Date.DaysInMonth(y,m)
            Dim fd As Date = New Date(y,m,1) '获得该月的第一天
            Dim ld As Date = New Date(y,m,Days) '获得该月的最后一天
            Dim bh As String = e.DataRow("类别") & "-" & Format(d,"yyyyMM") & "-" '生成编号的前缀
            If e.DataRow("销售编号").StartsWith(bh) = False '如果单据编号前缀不符
                Dim max As String
                Dim idx As Integer
                Dim flt As String
                flt = "类别 = '"& e.DataRow("类别") & "' And 销售日期 >= #" & fd & "# And 销售日期 <= #" & ld & "# And [_Identify] <> " & e.DataRow("_Identify")
                max = e.DataTable.Compute("Max(销售编号)",flt) '取得该月的相同工程代码的最大单据编号
                If max > "" Then '如果存在最大单据编号
                    idx = CInt(max.Substring(12,4)) + 1 '获得最大单据编号的后四位顺序号,并加1
                Else
                    idx = 1 '否则顺序号等于1
                End If
                e.DataRow("销售编号") = bh & Format(idx,"0000")
            End If
        End If
End Select

请问前辈老师：一样的代码，表A能自动编号，而表B则不能，不知为什么，请前辈老师帮忙看一下，谢谢！

报什么错？

  idx = CInt(max.Substring(12,4)) + 1

改成

  idx = CInt(max.Substring(bh.length,4)) + 1 '

谢谢老师！请问这是为什么呢？

bh不能定死为12。

现在报什么错？