CommandButton startet UserForm nicht

Private Sub CommandButton1_Click()
UserForm1.Show
End Sub

Private Sub UserForm_Initialize()
Dim rng As Range
With Sheets("Vorgaben")
For Each rng In .Range(Cells(1000, 1).End(xlUp).Offset(0, 0), Cells(2, 1))
UserForm1.ComboBox1.AddItem rng
Next
For Each rng In .Range(Cells(1000, 2).End(xlUp).Offset(0, 0), Cells(2, 2))
UserForm1.ComboBox2.AddItem rng
Next
For Each rng In .Range(Cells(1000, 3).End(xlUp).Offset(0, 0), Cells(2, 3))
UserForm1.ComboBox3.AddItem rng
Next
For Each rng In .Range(Cells(1000, 4).End(xlUp).Offset(0, 0), Cells(2, 4))
UserForm1.ComboBox4.AddItem rng
Next
End With
End Sub