Serial Number Do Nero Vision 3.1.0.25 Why Cant I Update Nero 7? Please Help!!?

Why cant I update Nero 7? Please help!!? - serial number do nero vision 3.1.0.25

I edit and burn AVI files in Nero Vision, but it is said that the need to allow some license keys to activate MPEG-4 or something like that. I was entered in the middle of the updated Nero and my serial number, but say their validity. Why is this so? I have not bought that copy of Nero where it came free with the DVD recorder. How to Nero so I can get the MPEG-4 capability? I want a new copy?