Reesie is a little devil about it, too. She'll go pee & poop outside, or wherever she wants. Most times she'll yap at me and then get all excited when I say 'Wanna go potty?' and I'll take her out with Cindy. Other times she finds her favorite spot inside and on the sly.
But it may be something with the Terrier breed. Here's a picture of my old Ginger who was a Terrier of some sort but a wonderful girl. She just loved me for all she had but hated the feel of grass on her feet and peed in the house no matter how we tried to train her. Same with Reesie, there's something about the grass tickling her toes that she hates and that makes the potty training hard.
You are not alone in your frustration.
http://www.yorkietalk.com/forums/mem...-go-heaven.jpg