I just bought a new Piezo pickup for my acoustic guitar. and i installed it. i went to plug it in and as i expected, there was a ton of feedback. so, i went to my local guitar store today, and bought a feedback buster. i put that over the soundhole, and went to play it through my amp. and unfortunately, i still get the feedback. the amp goes up to a certain volume, but after that, the feedback just destroys anything i try to play.
as you can imagine, im very upset. what is the deal?

anybody? help!

Use something like a Zoom A2 pedal. It has a feature on it that stops feedback by lowing some frequency when appropriate or something like that. Read up on it man.

Feedback is an inherent problem with amplified acoustics. Mess with your tone controls to help minimize it (or try what boggle3 suggested). Also try different locations for your amp or PA speakers. Like in front of you with the speaker pointed in the direction of where the audience would be. (Sometimes also slightly angled up, towards where the back wall meets the ceiling, will help as well.) Also, as you get used to it, you'll sort of find ways to minimize it as you play, like sort of muting unused strings, firmer contact with the top, etc. Feedback is always a potential problem with acoustic guitars, esecially in smaller rooms.

like this http://www.bossus.com/gear/productdetails.php?ProductId=157 ???

Yeah that would be great, says it has a built in feedback eliminator so that would do the trick. Also has some other features to play with too.

I can almost guarantee you won't like your tone if you use one of those gadgets.