typically that error is one of three things.

either (1) the tracker is down. (this is the most common reason, you can try checking animesuki's main page to see if the tracker is responding to people in general or not).
(2) your isp or your personal firewall is blocking the port. If this were the case, you'd be unable to download anything from a tracker that uses that port, but that's also pretty uncommon.
(3) your dns lookup of the tracker returned an invalid result (ie: the tracker resolves to localhost) Try nslookup gotwoot.net (from a command window) and see if it resolves to something like 127.0.0.1 or 192.168.0.1 or something else that isn't routable. Typically though, this sort of thing would be your isp too, or your hosts file. Might be worth a check but probably not.

At least, that's been my experience with it. Tracker appears to be up and running right now, but I don't know about when you posted your question.