SMS wrote:
We have either a mouse or a roof-rat running around inside the attic.
You can hear him (or her) mainly early in the morning.

I set a trap with peanut butter on a piece of bread as the bait. So far
no mouse, but it's only been an hour.

Any other advice on how to catch him (or her) would be appreciated.

The trap I bought is the following:

http://tinyurl.com/d8ruyg

Try using a stinky smelling cheese as bait.

It would be a good idea to smoke the trap to remove human scents.

5-1/2" height and width may not be large without if it's anything
larger than a roof rat.