It seems like you're facing an issue with activating your trial version of 3ds Max using the serial number for the registered version. Here are some steps you can take to troubleshoot and resolve this problem: 1. Check Serial Number Compatibility: Ensure that the serial number you have is compatible with the version of 3ds Max you are trying to activate. Sometimes, different versions require specific serial numbers. 2. Run as Administrator: Try running 3ds Max as an administrator to ensure that it has the necessary permissions to write the serial number to the activation window. 3. Compatibility Mode: If you're using an older version of 3ds Max on a newer operating system, try running the software in compatibility mode to see if that resolves the activation window visibility issue. 4. Reinstall the Software: If none of the above steps work, consider reinstalling the software. During the installation process, make sure to input the serial number for the correct version. 5. Contact Autodesk Support: If the issue persists, it's best to reach out to Autodesk Support for assistance. They can provide you with more specific guidance tailored to your situation. By following these steps, you should be able to address the blank activation window issue and successfully activate your 3ds Max software.