If you decide to continue with outside...when you take him out there...walk him around. Walking stimulates them to go which is probably why he comes by inside and goes. I would also suggest a potty phrase....walk him around and repeatedly say go potty (or whatever phrase)...when he goes, praise to high heaven and give him a treat.
When mine first got it....going to the door was the first sign. Unfortunately like yours...if you didn't see them at the door...they went BY the door.
__________________ Deb, Reese, Reggie, Frazier, Libby, Sidney, & Bodie |