One more silly ? re proofing yeast

When I follow the recipe to make pizza dough I always proof the yeast. Every
single book I have read says that it will "foam up" or "bubble up." I have
checked the dates, I know the yeast has not expired, but i'll be darned if I've
ever seen the yeast "bubble OR foan." I kept it in a warm place for as long as
they say. The pizza comes out ok, but not the high rising deep dish kind Im
looking for. HELP!!! All the ingredients to make the pizza ( I like the gourmet
specialty kind) are expensive. I feel like I keep wasting money. I use a pizza
stone, I thought that might help, but no. Thanks for your help!