Invalid activation code PS Elements 9

Hello,

I haven't used my PhotoShop Elements 9 for quite some time (I un-installed it from my Mac a few years ago) .Today I decided to install it on a different computer, Windows 10. I have the program on a CD, and I have the serial number that went with the CD.  The product is registered in my Adobe account, with the same serial number.

Installation seems to go fine, until I get a message saying the serial number is wrong.

What can the reason be?

Thanks