Princess may be confusing the treats with her act of "kicking up the dirt" (it is sooo cute when they do that isn't it???
, I have a bull kicker too, lol), rather than the act of going potty on the pad.
I think the best way to get her to make the connection is to treat/praise her right when she steps off the pad after going, which means you will have to see her doing it.
and yes, they can be con artists (smart ones!) too, hehehe.