Hrmmm... I'm guessing that you're opening up the trial copies instead of the real one.... Open your hard drive and then open your applications folder. View it by list, or alphabetically. You'll probably see folders like "iWork" and "iWork Trial"... Trash the "Trial" Folders, and open up the "iWork" folder and add those apps to your dock.
The trial copy converts to a fully-functional copy simply by typing in the registration code. Absolutely not necessary to uninstall anything (unlike Microsoft and their goofy test drive)
I suspect that the registration number is not entered properly. iWork is known to use the letter 'O' in the license code. If you think you see a number zero, try the letter 'O' instead. I'm betting that will work for you. This also happened for me, and I thought I had a bum copy, but it was just needing the 'O'. Strange for Apple to do that, eh?