Listview not locking

[BestCoder]

Hi... I am using the LockWindowUpdate API to lock a listview... however it does not seem to be working. I am locking a Treeview at the same time and it works but not the listview. When I try to lock the listview the LockWindowUpdate function returns 0... Any ideas??? Here's my code minus the API Declaration:

Private Sub Listview_DblClick()
    Dim retval as Long
 
    retval = LockWindowUpdate(TreeView1.Hwnd) 'returns 1
    retval = LockWindowUpdate(ListView1.Hwnd) ' returns 0
End Sub

Thanks....

BestCoder