I had to really work to get Leo's ear to stand- Mia's popped up without any problem right after I shaved them. Leo's didn't though, his ears are a little bigger and they are thinner than hers. I tried several different methods, but this website is the one that worked for me...
http://members.aol.com/CYorkie/TapingEars.html
I ended up having to tape his ears three different times to get them to stay up.
Hope this helps!