MacBook won't see my room, or won't mirror:
1. The first thing to always try when having AirPlay issues is to save all your work and restart your MacBook.
2. If that doesn't solve the immediate issue, are you still able to connect using your iPad?
3. If the iPad isn't seeing or connecting to your AppleTV either, is the AppleTV "Home Screen" visible on the television? Press "Menu" on the AppleTV remote (thin silver one) several times to get it to wake up.
4. If the AppleTV isn't showing up, please contact IT. It may be disconnected or broken.