I found this info at the Taste of Home site on reasons why bread dough might not rise. I'm not sure if I should just quit already.
1. Your yeast is old. If your yeast is too old, chances are you aren't going to get a good rise.
2. The water is too hot. Anything hotter than 105 degree to 115 degrees F could kill the yeast.
3. It's too cold inside. If your kitchen is too cold, the yeast could die.
4. You added too much salt. Too much salt can keep the yeast from doing its job. Never pour yeast and salt on top of another in your mixing bowl.
5. You added too much sugar. If you added too much sugar in your dough, chances are that it will gobble up almost all of the food the yeast needs, leaving you with dry, ineffective yeast.
6. You added too much flour. Too much flour can make your dough stiff and dry. If there's not enough liquid present it doesn't work the way it should.
7. You're using whole grains. Whole wheat and other alternative flours don't develop gluten as easily or at all.
8. The crust is too dry. If a crust develops on top of the dough, it can be difficult for the bread to rise.