i had that problem for a little while too with cainan! What i started doing was walking around the yard with him instead of just standing there and waiting! or i take a short walk down the block. He eventually realizes he has to pee once we start walking. So while he's going i get REALLY excited that he went, and i just keep saying "good boy cainan, good boy" after a few times he finally started to understand that when you let him outside he goes pee! he distinguishes outside=pee, instead=no pee! try walking around with him, sometimes you may have to walk further, just depending! good luck!!