More information please.
What version of Premiere Elements and on what computer operating system?
Is this a reinstall or a first time install of the program? If a reinstall, you can go to the Adobe web site, sign in, type "My Products" in the
search field, and follow the "My Products" to a list of products that Adobe has registered for you. When you get to that list, click on the name of your product to
bring up the serial number. Does it agree with the one that you are trying to use?
We will be watching for further information and your progress.
Any questions or need clarification, please do not hesitate to ask.