On Error Resume Next

Dim strSQL As String

strSQL = "SELECT Mat_Id, Mat_Name FROM tblMaterialart " & _
"WHERE Mat_Name LIKE '*" & txtSuchbegriff & "*' " & _
"ORDER BY Mat_Name"

lstMaterialarten.RowSourceType = "Table/Query"
lstMaterialarten.RowSource = strSQL
lstMaterialarten.Requery

If Nz(lstMaterialarten.ListCount) > 0 Then
Me!lstMaterialarten = Me!lstMaterialarten.ItemData(0)
Call lstMaterialarten_AfterUpdate
End If