Potentiometer voltage range?

[flameout]

How is it wired up?

If it is a 3-pin potentiometer, then one should be connected to ground, one to 5v, and the sweeper to the analog input.

A potentiometer acts as a voltage divider -- it needs a ground and 5v to function. It sounds as if you might not have ground connected.

If ground is connected, take out a multimeter and check the resistances. Two leads should have a 100-ohm resistance between them (no matter where its input is). It is also possible that you wired 5v to the sweeper arm, 0v to one of the other pins, and the analog input to the last.

Also, once you've verified that it's wired right, check it with the voltmeter. Maybe it's a software issue (i.e. reading from the input next to where it's connected).

I hope this helps.