Search as you type not working

I would like to to search a listbox that has been populated by a query (which I saved in Access as qyrKunde_Suchen):

SELECT tblkunden.kundenid,
       tblanreden.anrede,
       [nachnameoderfirma] & "" & [vorname]                       AS Kunde,
       [strasse] & "" & [strassennr] & "," & [plz] & "" & [ort] AS Adresse,
       tblkunden.telefon,
       tblkunden.handy,
       tblkunden.email,
       tblkunden.info,
       tblkunden.aktiv,
       tblkunden.isteinmalkunde
FROM   tblanreden
       INNER JOIN tblkunden
               ON tblanreden.id = tblkunden.tblanreden_id
WHERE  (( ( [nachnameoderfirma] & "" & [vorname] ) LIKE
                  "*" & [formulare] ! [frmsuchen] ! [txtcustomer] & "*" ))
        OR (( ( [strasse] & "" & [strassennr] & "," & [plz] & "" & [ort] )
              LIKE "*"
              &
                   [formulare] ! [frmsuchen] ! [txtcustomer] & "*" ))
        OR (( ( tblkunden.telefon ) LIKE "*" & [formulare] ! [frmsuchen] !
                                         [txtcustomer] &
                                             "*" ))
        OR (( ( tblkunden.handy ) LIKE "*" & [formulare] ! [frmsuchen] !
                                       [txtcustomer]
                                       &
                                       "*"
                ))
        OR (( ( tblkunden.email ) LIKE "*" & [formulare] ! [frmsuchen] !
                                       [txtcustomer] &
                                       "*"
                ));  

Select allOpen in new window

So the form is called frmsuchen - and the the search textbox is called txtcustomer.
The listbox is called lstCustomer.

I would like to requery every time the user types something in the textbox. I used the following code:

Private Sub txtSearch_Change()
    Me.lstCustomers.RowSource = "qyrKunden_Suchen"
End Sub

Select allOpen in new window

But nothing happens.
Isn't this query supposed to put the appropriate search text into the WHERE clause of the query?

I am using a German version of Access - hence the [formulare] and not [forms] in the SQL query.

ShoppingTaxi-EE.accdb