I thought that was part of the definition of a Yorkie 

 !   
Potty time for Bailey -  
Bailey:  Walk around, sniff, dig, dig, dig  
Me: Bailey, go potty  
Bailey:  Walk around, sniff, dig, dig, dig  
Me:  Bailey! GO POTTY! 
(Repeat half a dozen times with less walking and sniffing each time, but more digging!) 
When she finally does go, she comes to grab her treat and immediately runs back to her diggin' spot - at which time I grab her and head back in.