主题：为什么不起作用

 上传具体例子，或者加入msgbox调试

别的表 Datacolchanging 事件有影响

Select Case e.DataCol.Name
        Case "出库单号"
            Dim bmcls As List(Of String) = DataTables("部门信息表").GetValues("领用单位表名")
            For Each  bmcl As String In bmcls
                If DataTables.Contains(bmcl) Then
                    Dim dh As DataRow = DataTables(bmcl).Find("[出库单号] = '" & e.NewValue & "'")
                    If dh IsNot Nothing Then
                        e.Cancel = True
                    End If
                    'Dim ckdh As DataRow = DataTables(bmcl).Find("[出库单号] = '" & e.NewValue & "'")
                    If dh Is Nothing Then
                        'Dim bms As List(Of String) = DataTables("部门").GetValues("部门类别")
                        ' For Each  bm As String In bms
                        '  If DataTables.Contains(bm) Then
                       
                        If e.DataRow("记账") = True And e.DataRow("分配表名") = bmcl Then
                            Dim nma() As String = {"物料代码","物料名称","规格型号","常用计量单位","加权平均单价","出库数量","出库金额","出库日期","出库单号","作业项目","成本项目","材料用途","领用人"} 'A表数据来源列
                            Dim nmb() As String = {"物料代码","物料名称","规格型号","常用计量单位","加权平均单价","出库数量","出库金额","领用日期","出库单号","作业项目","成本项目","材料用途","领用人"} 'B表数据接收列
                            Dim dr As DataRow = DataTables(bmcl).AddNew()
                            systemready = False
                            For i As Integer = 0 To nma.Length - 1
                                dr(nmb(i)) = e.DataRow(nma(i))
                            Next
                            systemready = True
                        End If
                        ' End If
                        ' Next
                    End If
                End If
            Next
    End Select

 你原本想做的是不是这个意思？

    Select Case e.DataCol.Name
        Case "部门类别"
            Dim fdr As DataRow = DataTables("部门信息表").Find("部门类别 = '" & e.DataRow("部门类别") & "'")
            If fdr IsNot Nothing Then
                e.DataRow("分配表名") = fdr("领用单位表名")
            End If
           
    End Select

9楼已经告诉你了。别的表的Datacolchanging事件影响了。

Select Case e.DataCol.Name
    Case "出库单号"
        If e.DataRow("记账") = True Then
            If DataTables.Contains(e.DataRow("分配表名")) Then
                Dim dh As DataRow = DataTables(e.DataRow("分配表名")).Find("[出库单号] = '" & e.NewValue & "'")
               
                If dh Is Nothing Then
                   
                    Dim nma() As String = {"物料代码","物料名称","规格型号","常用计量单位","加权平均单价","出库数量","出库金额","出库日期","出库单号","作业项目","成本项目","材料用途","领用人"} 'A表数据来源列
                    Dim nmb() As String = {"物料代码","物料名称","规格型号","常用计量单位","加权平均单价","出库数量","出库金额","领用日期","出库单号","作业项目","成本项目","材料用途","领用人"} 'B表数据接收列
                    Dim dr As DataRow = DataTables(e.DataRow("分配表名")).AddNew()
                    systemready = False
                    For i As Integer = 0 To nma.Length - 1
                        dr(nmb(i)) = e.DataRow(nma(i))
                    Next
                    systemready = True
                   
                End If
            End If
        End If
End Select