Home → FolderSizes FAQ → Product Registration → My registration details aren't working
1.2. My registration details aren't working
The most common cause of this problem is that you're trying to register an installed version of FolderSizes that's different from the one you actually purchased.
For example - if you purchased the new FolderSizes version 4.0 release, the product registration details you receive will only be valid for version 4.0 (the serial name / number will not work with version 3.x). In this case, you'll need to download and install FolderSizes version 4.0, which you can then "unlock" with your serial name / number.
If you purchased FolderSizes 3.x, your existing product registration details will not work with the new v4.0 release. You have two choices:
- Download and install FolderSizes v3.x, which will accept your registration details
- Upgrade to FolderSizes version 4.0 (special upgrade pricing is available)
Finally, we always recommend that you use the Windows clipboard to copy and paste your product registration information into the software. The serial name / number combination are mathematically linked, and they must be entered exactly as they are given to you.