Ungültiger Bezeichner

Function GetImage(UserForm1 As UserForm, imtop As Integer, imleft As Integer) As String
Dim cntl As Control
For Each cntl In UserForm1.Controls
If TypeName(cntl) = "Image" Then
If cntl.left = imleft And cntl.top = imtop Then
GetImage = cntl.Name
Exit Function
End If
End If
Next cntl
GetImage = ""
End Function

Sub schieben()
Dim x As String
Dim y As Control
Dim imtop As Integer
Dim imleft As Integer
imtop = 30
imleft = 30
x = GetImage(UserForm1, imtop, imleft) ----> liefert x = Image1
x.left = x.left + 20                   ----> sollte das bild um 20 schieben
liefert aber den Fehler!
End Sub