Hardware Help with psp bottom buttons!

[kokiri_link]

Basically a while ago, i replaced my psp faceplate with a clear one (as the original was damaged), Since i have put it back together, the bottom set of buttons are not working. By this i mean the home, volume, brightness, music and select ones, the start button however works flawlessly. I've replaced the buttons with a new set, to no avail, anybody know what's happening? Or has anyone had the same problem?

Its a bugger, cause i cant put ps1 games into full screen >:[