I can't, either, and Properties set in errant Form's Properties Pane has nothing to do with how it opens, using a Command Button, that's why you have to use the Form View Parameter of acFormDS.
When things that patently should work are found to not work, you simply have to think about corruption! First thing, I'd do, after saying a prayer to the Access Gods (or maybe the Access Gnomes!) would be to delete your current Command Button and re-create it. It's simple enough to do, and would rule out whether or not it is the Command Button Control that is corrupt. CB's cand and do get corrupted, on a regular basis, during development.
Linq ;0)>
The problem with making anything foolproof...is that fools are so darn ingenious!
All posts/responses based on Access 2003/2007