主题：窗口筛选问题

我窗口有两个组合框控件，分别绑定在要筛选表的父表相关列，怎么在控件ValueChanged和TextChanged事件中设置如下代码，都不成功。
Dim Filter As String
With e.Form.Controls("图号")
    If .Value IsNot Nothing Then
        Filter = "图号 = #" & .Value & "#"
    End If
End With
With e.Form.Controls("序号")
    If .Value IsNot Nothing Then
        If Filter > "" Then
            Filter = Filter & " And "
        End If
        Filter = Filter & "工序_序号 = '" & .Value & "'"
    End If
End With
If Filter > "" Then
    Tables("产品工艺").Filter = Filter
End If