Not possible to extend series on data validation cells in protected sheet.

[Krulle1000]

I would like to protect shapes so I use the argument DrawingObjects:=True.
However, with this argument set, it's not possible anymore to extend series on cells with a data validation list.
In example, click on cell A1 and autofill the data to cell A10 won't work.
The hand mousepointer appears instead.
When DrawingObjects:=False it works fine
Any thoughts how to solve this problem?

Private Sub Workbook_Open()
Sheet1.Protect "password", UserInterfaceOnly:=True, DrawingObjects:=True
End sub

Thanks,
Jurgen.