Q: OS X 10.8.5 Cannot use Ethernet even with the adapter

Hi everyone,

I recently moved in my university's halls of residence where there's no wifi: we use ethernet. Since I own a macbook air I had to buy an Apple Thunderbolt to Ethernet adapter, but i'm still not getting internet. I asked one of my flatmate to plug his laptop with my ethernet cable and it worked perfectly fine, which means the problem can only come from the adapter or my laptop... What can I do to fix this??

Thanks