I have a broken CD version of Movie Studio 16, I registered it when I purchased and when I recently inserted the serial number from your website, the serial number is not valid. The original computer died and I wanted to load to my newest computer.
Under My Products you should find your registered MV16 where you can download the last build and check the serial number (you don't say which "your website" you obtained it from). Note that your MV16 will be registered to the email address you used at that time and the serial number associated with that email. So if you are trying to use a different email it won't work.
Also please note we are a user to user forum not Magix.