Re: My old serial number don't work on my new PC, but I have uninstalled it from my old? Photoshop Elements 7

You can use one serial number only on two machines at a time.

As suggested by Benjamin, It is advisable to deactivate PSE 7 first from your old machine and try activating it on a new machine.

Let us know if you need more help.

Thanks,

Anwesha