Tires Not Taking in Air But Will Let Air Out
You may simply not pushing the pump onto the value body enough, and the internal valve is not being opened. 

Most pumps have a plastic insert behind the valve hole that is reversible for Schrader or Presta value use.



[Schrader left Presta right.]

This insert may be the wrong way around, or (as has often happened to me) the small peg that opens the Schrader valve has been bent so it no longer pushes on the valve.