主题：窗口代码问题

请问我在点击主表目录树节点时，出现如下错误提示：

此主题相关图片如下：未命名.gif

窗口控件姓名和年月都是绑定到主表列，控件ValueChanged代码如下：

Dim Filter As String
With e.Form.Controls("姓名")
    If .Value IsNot Nothing Then
        Filter = "姓名 = '" & .Value & "'"
    End If
End With
With e.Form.Controls("年月")
    If .Value IsNot Nothing Then
        If Filter > "" Then
            Filter = Filter & " And "
        End If
        Filter = Filter & "年月 = '" & .Value & "'"
    End If
End With
Dim dd As WinForm.TextBox = e.Form.Controls("年月")
Dim dd1 As WinForm.TextBox = e.Form.Controls("姓名")
Dim Filter1 As String
With e.Form.Controls("姓名")
    If .Value IsNot Nothing Then
        Filter1 = "姓名 = '" & .Value & "'"
    End If
End With
With e.Form.Controls("年月")
    If .Value IsNot Nothing Then
        If dd1 IsNot Nothing Then
            Dim d1 As Date = DataTables("主管考勤").Compute("min(日期)", "[姓名] = '" & dd1.text & "' And [年月] = '" & dd.text & "' ")
            Dim dr As DataRow = DataTables("主管考勤").Find("[姓名] = '" & dd1.text & "' and [日期] =  #" & d1.AddDays(-10) & "# ")
            If dr IsNot Nothing Then
                If Filter1 > "" Then
                    Filter1 = Filter1 & " And "
                End If
                Filter1 = Filter1 & "年月 = '" & dr("年月") & "'"
            End If
        End If
    End If
End With
If Filter > "" Then
    Tables("主管考勤月统计查询_Table1").Filter = Filter
End If
If Filter1 > "" Then
    Tables("主管考勤月统计查询_Table2").Filter = Filter1
End If
Tables("主管考勤月统计查询_Table1").Sort = "日期" '排序
Tables("主管考勤月统计查询_Table2").Sort = "日期" '排序