1) Click on My Account and make sure your Gmail address is correct.
2) Re-Enter your Gmail password and hit save.
3) Go to your Google Calendar and make sure you see an appointment labeled "Google Calendar Connected Successfully!"
4) Look to the left hand side. Under "My calendars", and make sure the box next to YOUR name is highlighted.
If your Mhelpdesk appointments still aren't showing after you've completed these steps, please submit a ticket.