If you built a project with an old version of Mockplus with the extension ".mp" and you want to suika game open it with a newer version, the process should be straightforward. Here are the general steps:

1. Install the New Version: Ensure that you have the latest version of Mockplus installed on your Windows system. You can download it from the official Mockplus website.

2. Open the New Version: Launch the new version of Mockplus on your computer.

3. Open Project: In the new version, look for an option like "Open Project" or "Import Project." This is usually found in the File menu.

4. Select the ".mp" File: Navigate to the location where you have saved your old project with the ".mp" extension. Select the file and click "Open" or "Import."

5. Conversion (if needed): The newer version of Mockplus may automatically convert the old project to a format compatible with the latest version. Follow any on-screen instructions for the conversion process.

6. Review and Save: Once the project is open, review it to ensure that everything is intact. Make any necessary adjustments if prompted by the conversion process. Save the project in the new version.

If you encounter any specific issues during this process, you may want to refer to the Mockplus documentation or contact Mockplus support for assistance. Additionally, check if there are any release notes or documentation related to version updates, as there might be specific guidance on upgrading projects from older versions.

Remember to backup your old project before attempting to open it with a new version, just in case there are unexpected issues during the conversion process.

Do you use Mockplus classic before?  If this is the case, you can refer to this tutorial: https://www.mockplus.com/community/all/all

If you use Mockplus rp before you can refer to this image. 

Please try this. And let me know if you still have a problem.