IPod Touch App update won't show up in 'Updates' in App Store.?

So here's the thing...there's an app called 'Tiny Tower' I WANT to play it. But however the update isn't showing up in my 'Updates' tab in the 'App Store', and I've plugged it into my iTunes I have the latest iTunes blah blah blah...it showed up once before. And I was about to do it, but then something happened and I don't even remember what happened it was there and everything and now it's gone. I'm really peaved off!! PLOIZE help me!! I'm gunna throw this thing out the window!!!