Cannot access external hard drive from airport.

I have a g5 mac book pro. an airport extreme base station. and a my book external hard drive.

i used to have no problem getting the hard drive to show up on my desktop. but after fooling around and maybe clicking something wrong, it wont show up!!!! any advice?

opps ! i should also meantion that im plugging my external into my base station so i can access it wirlessly from anywhere in my house!