Replacement screen works but not naturally

HEY !

A year ago my iBook G4 12" 1.33ghz (A1133) fell after someone tripped over the networking cable, ironically while i was out buying an Airport Express base station.

The Hinge snapped and the unsupported screen cracked under stress a month later.

I replaced the screen with an 1Book 12" G4 screen from this website (iFixit.com).

I have installed it. It works. There is one dead pixel but at 1024x768x32 resolution it operates perfectly.

HERE is THE PROBLEM: At the aformentioned resolution operation is fine. However, when i change the resolution, to say 800x600 or 640x680, The screen maintains the 1024x768 screen resolution and and reduces the displayed screen size within the screen.

I know it is not a big deal, but using any games or programs that use a different resolution make the computer unusuable. I paid for a replacement G4 screen, so i feel that i should have a fully functioning screen. This is important to me, please help me solve the problem.

Regards, Matthew