Here's a good link on how to tape ears, you don't say how old you puppy is, but sometimes this takes time, and it's important to clip the hair on the top third of the ear.
Top Taping Yorkie Ears Taping Yorkshire Terrier Ears Stand Erect Yorkie Ears Puppies whose ears have been erect sometimes fall around 6 months due to teething, and taping can work at that time as well. Here's a couple of threads on flopppy ears.
http://www.yorkietalk.com/forums/bre...ping-ears.html and
http://www.yorkietalk.com/forums/gen...bout-ears.html