If you pump it without putting it to a Schrader, or any, valve, does air come out? If yes, the thing that depresses and opens the Schrader valve might be busted and the air pressure generated is insufficient to open the valve. If that's the case, you can either try to fix the head, cut the head off and replace it, or replace the pump.

Replacement heads...
http://www.amazon.com/gp/product/B001CK2O3I
http://www.jensonusa.com/store/produ...alve+Head.aspx