Different Tire Pumps?

There are different pumps for different tubes. If you are currently using presta valves odds are that pump won't work.

See if you've got presta or schrader:
http://www.sheldonbrown.com/brandt/presta-schrader.html

If it turns out you have a presta valve but a schraeder pump, you can get a little adapter to fit over the valve and use the old pump.  Or if you want to invest in a new pump, get one that has both.  I prefer that kind of pump, with a gauge and a little doo-hickey that you can use to indicate the presure you want (since I have old person eyes and can't read the numbers that well).

In addition to the different values you cannot get the necessary tire pressure with a mountain bike pump.  You'll have to get a road bike pump.

You can find pumps that accomodate both types of valves, even find one that will know the difference for you.

I've had this one for a few years now.

Trot down to your local bike shop.
I have 2 pumps that have been solid- Topeak Joe Blow Pro and a Park home-duty pump.