I imported a private key to a wallet that was confirmed (by me and a third party) to have some Bitcoins in there, so when I went to import the private key for that address, it worked because now in my wallet, Bitcoin QT, under the receive tab, the address that corresponds to the private key that I imported was there, but the bitcoins that are still in the address are not showing up in my wallet..

Any idea what is causing this to not show up?