In order for us to understand what exactly is wrong in your case, can you please do the following:
1. Right Click "My Computer" icon and click Properties.
2. Click Advanced System Settings
3. On Advanced Tab click Environment Variables
4. In System Variables click New and add following:
Variable Name: VSTO_SUPPRESSDISPLAYALERTS
Variable Value: 0
5. In Outlook, try to re-enable the Method Outlook Plug-in from the window you attached in your screenshot.
6. You will get a more detailed error message. Please copy-paste the error message to this forum and we will investigate it.
Thank you and sorry for all of this trouble