Troubleshooting "can't connect to host"

[jtmiv]

When I try to connect to test.ninjam.com:2050, it attempts to connect for ten to fifteen seconds, then prints "can't connect to host". What could be causing this problem?

Info:
Running Mac OS X 10.4.10 with NINJAM 0.02a.
I'm using a Macbook with a wireless internet connection.
The Jam Farm states that there are two users on test.ninjam.com:2050.

[jtmiv]

I forgot to open the necessary ports on the Mac OS X firewall. Sorry, guys.

[NIGHTCHILD]

you will also get that message if the room is full.. 6 max