My bet is that your university/academy runs the net over a VPN. Which means that you'll either have to connect to it with a browser, to login, or use the usual Windows XP VPN dial-up. I do not own a DS, but I doubt that they support VPN connections and thus you'll most probably have little success.

However, try connecting to the network without a WEP, as it might be unsecure. If it doesn't work, forget it.