主题：实现“入库单在保存时自动生成会计凭证”

老师：你好，我这段代码点“已记账”为什么在总账里会增加两个空行

If e.DataCol.name = "已记账" Then
    If e.NewValue = True Then
        Dim lb As String = e.DataRow("凭证号")       
        For Each km As String In DataTables("凭证明细表").GetValues("借方一级科目","[凭证号] = '" & lb & "'")
            Dim filter = "[凭证号] = '" & lb & "' and [借方一级科目] = '" & km & "'"
            Dim fdr As DataRow = DataTables("总账").Find(filter)
            If fdr Is Nothing Then
                fdr = DataTables("总账").addnew
                fdr("日期") = e.DataRow("日期")
                fdr("凭证号") = e.DataRow("凭证号")
                fdr("借方一级科目") = km
            End If           
            fdr("借方金额") = DataTables("凭证明细表").Compute("sum(借方金额)", filter)
        Next
        For Each kmt As String In DataTables("凭证明细表").GetValues("贷方一级科目","[凭证号] = '" & lb & "'")
            Dim filter1 = "[凭证号] = '" & lb & "' and [贷方一级科目] = '" & kmt & "'"
            Dim fdr1 As DataRow = DataTables("总账").Find(filter1)
            If fdr1 Is Nothing Then
                fdr1 = DataTables("总账").addnew
                fdr1("日期") = e.DataRow("日期")
                fdr1("凭证号") = e.DataRow("凭证号")
                fdr1("贷方一级科目") = kmt
            End If
            fdr1("贷方金额") = DataTables("凭证明细表").Compute("sum(贷方金额)", filter1)           
        Next
    Else
        Dim dt1 As DataTable = DataTables("总账")
        Dim lb As String = e.DataRow("凭证号")
        dt1.DeleteFor("凭证号 = '" & lb & "'")
       
    End If
   
End If

两行空行

设置的，按照自由设置好友例子 我在 服务端 窗口的AfterLoad事件写代码：

Dim trv1 As WinForm.TreeView = e.Form.Controls("TreeView1")
Dim trv2 As WinForm.TreeView = e.Form.Controls("TreeView2")
Dim trvs() As WinForm.TreeView = {trv1,trv2}
For Each trv As WinForm.TreeView In trvs
    For Each u As UserInfo In Users
        If u.Type = UserTypeEnum.User Then
            If trv.Nodes.Contains(u.Group) = False Then
                trv.Nodes.Add(u.Group)
            End If
            trv.Nodes(u.Group).Nodes.Add(u.Name)
        End If
    Next
Next
trv2.CheckBoxes = True '右边目录树显示复选框

预览后，出现”  .NET Framework 版本：2.0.50727.8784

Foxtable 版本：2018.3.9.1

错误所在事件：窗口,选择好友,AfterLoad

详细错误信息：

未将对象引用设置到对象的实例。“请问老师我要怎样写代码才对，谢谢老师指导！

这样测试，看弹出什么

For Each trv As WinForm.TreeView In trvs
    For Each u As UserInfo In Users
        If u.Type = UserTypeEnum.User Then
            msgbox(u.group)
            If u.Group > "" Then
                If trv.Nodes.Contains(u.Group) = False Then
                    trv.Nodes.Add(u.Group)
                End If
                trv.Nodes(u.Group).Nodes.Add(u.Name)
            End If
        End If
    Next
    msgbox(trv.nodes.count)
Next