Dictionary gibt keinen Rückgabewert

Private Sub worksheet_change(ByVal target As Range)
Dim key As String
If IsNumeric(target) And target  "" Then 'only need to be done if there is a value and if the value is numeric
key = Me.Cells(target.Row, [tbl_log_main].Cells(1, 1).Column + 4)
Debug.Print VarType(Me.Cells(target.Row, [tbl_log_main].Cells(1, 1).Column + 4)) ' ergibt 8 = String
target = KV_ops(Me.Cells(target.Row, [tbl_log_main].Cells(1, 1).Column + 4)) & " " & target 'das geht nicht
'target = KV_ops(key) & " " & target 'das geht
End If
End Sub