Why is my puppy afraid of the grass now?

We have been working on potty training our 4 month old shar pei for the past 2 weeks. We praise him crazily when he goes outside. We also have a 10month old husky that we are still working on potty training as he is just NOT getting it. It started yesterday after it rained the grass was wet and we had to drag our shar pei out in it because he wouldn't go. Now today we still have to drag him into the grass...any advice as to why he is now doing this?? Any ways on fixing it?? He also seems like he doesn't really want to go outside at all anymore as well.