Brakes!

I just changed my 2003 Cavalier alternator and now my brakes will not pump. It feels like I am trying to push them in while the car is off, but it is started. I took all parts back off the car and checked over the work I have done (cables and plugs) just to ensure that everything was plugged in, but still the same result. I am really at a stand still and can't figure out what would cause that. Any help would be much appreciated.