I don't think you said which model of PowerBook this problem exists on, but ensure you get the correct LCD for the device you own. Ideally unscrew/disconnect/remove the LCD screen assembly off the base and then remove the back, carefully, to see which model screen it is that you need, as the LCD details should be on there. Though I'll probably be able to work out which screen you need if you let me know the model you have - if that's easier for you.