Yes, I can download files with other things like http, ftp, and etc. The same thing happens on someone else computer on campus.
Then it's obvious that, intentionally or not, the school's system is blocking dcc receive. If they want to solve the problem, work with their IT people (you know more about how to initiate a dcc receive than they do). If they don't want to solve it, you're out of luck while at school unless you get your own internet connection.