Kareberry has covered the steps very well, but I'll add some others...
Keep in mind that our Yorkies are basically little "Scent Hounds"
When they "carry" the scent of pee/poop with them, it can effect their perception of their whereabouts. That being in a Living Space, or a Potty Space. Trust me, Yorkies want to be clean, and have those areas separated.
It's probably going to be hard to keep up with, but try to give her Paws a quick rinse, when you see evidence of Potty activity.
Also, you might reevaluate the type of Pad you're using. Maybe try to select one which is more absorbent, and gets the liquid out of the way a bit quicker.
Put some treats in the Living Space of the Pen, and possibly make the Potty Space a bit smaller. You might even make a little separation between the two, like rolling up a towel and making Jessie step over it to get to the Potty Area.