主题：[求助]想对下拉表的数据筛选下再下拉 总是有一个参数没有被指定值

如下代码我写在下拉窗口的dropdownopening事件中 请老师帮忙看看

Dim f1 As String = Forms("电容料号录入").Controls("ComboBox17").Value
Dim f2 As String = Forms("电容料号录入").Controls("ComboBox18").Value
Dim f3 As String
Dim Filter As String
If f1 = "散件" Then
    If f2 = "环氧" Then
       f3 = "9"
       Else
       f3 = "12"
    End If
 Else
    If f2 = "环氧" Then
       f3 = "10"
    Else
       f3 = "11"
    End If
End If

 Filter = "默认工艺路线_FInterID=f3"
 DataTables("物料表").LoadFilter = Filter
 DataTables("物料表").Load()