@Pelle-Norn

Welcome to the Magix user to user forums.

First, which version of Movie Studio do you have, and from where did you purchase it? An activation code is required only if you currently have a "voucher code" because you have bought the software, new, from a third-party seller.

However, the message Serial Number already used suggests that; either, you have bought a used copy from another user; or you are trying to reregister software that you have previously registered and so have now reached the limit of the maximum number of activations you are allowed.

So;

• If you now have a copy purchased from another user, only that user can inform Magix that the software registered to him/her has been sold to you and so should be deregistered from his/her account to allow you to register it for yourself.
• If the problem is you are trying to exceed the maximum number of activations allowed you need to do the following:
  1. Log into your Magix account
  2. Go to My products
  3. Find the listing for the version of Movie Studio you have, click on "Show more details". This will take you to a page listing all your current activations of the software.
  4. Deactivate any and all you no longer need.
  5. Log out of your account
  6. Wait a few minutes and then try again to activate your new installation.

Hopefully, you will now be able to fully register and activate your software but if you still have problems, please4 post back with full details, including screenshots of any error messages you see or, at least, the full wording of them.

HTH

Jeff
Forum Moderator