Hi there! I understand you're having trouble with the "Add Vehicle" feature not working in the MyNISSAN app. To help you better, could you share a bit more about what happens when you try to add your vehicle? For example, do you get any error messages, or does the app just not respond?

Meanwhile, I can guide you through some common steps to try fixing this:

1. Check Your Account: Ensure you’re logged into the MyNISSAN app with the correct credentials. Sometimes, logging out and back in can refresh your connection.

2. App Version: Verify that your MyNISSAN app is updated to the latest version available on your device, as older versions may have bugs affecting functionality.

3. Internet Connection: Make sure your device has a stable internet connection. Adding a vehicle requires communicating with Nissan’s servers.

4. Vehicle Connectivity: Confirm your vehicle has an active NissanConnect subscription and is properly connected to cellular services.

5. Restart the App & Device: Force close the app, then restart your phone or tablet. This can clear any temporary glitches.

6. Try Adding on Website: If the app still fails, try logging into your MyNISSAN account on a desktop browser at Nissan’s official site and add the vehicle there.

7. Clear App Cache (if possible): On your device settings, clear the cache for the MyNISSAN app, which helps if corrupted data is causing issues.

If you've already attempted some of these or see specific error messages, let me know, and we can dive into more detailed troubleshooting. Also, occasionally Nissan's servers might have temporary issues affecting this feature—should that be the case, a short wait then retry helps.

Would you be able to check these and tell me what's happening when you try to add your vehicle? That way, I can help you better!