Dim j As Integer 
Dim Index As Integer 
With List1 
     For j = 0 To .ListCount - 1 
            If .List(j) like "*" & Text3.Text & "*" Then  
                   .ListIndex = j
                   Exit For
            End If
     Next
     If .ListIndex <0 Then Msgbox "Kein Ergebnis"
End With

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
     (ByVal hwnd As Long, _
      ByVal wMsg As Long, _
      ByVal wParam As Long, lParam As Any) As Long
 
Private Const LB_FINDSTRING = &H18F
 
'Innerhalb der Funktion dann:
Dim RVal As Long
RVal = SendMessage(List1.hWnd,LB_FINDSTRING, -1, Byval Text3.Text)
If RVAL < 0 Then
     MsgBox "Kein Ergebnis"
Else
     List1.ListIndex = RVal
End If