Problem connecting to a server?

[Cavernace]

I have problems connecting to my friends server, the IP is correct, and I'm on a MAC OSX, I have no idea whats wrong, and wasn't sure if this was a bug or what thread to put it in. I'm kinda stirving for help cause I really wanna play on this server, but It just can't connect for some reason. Please, I'll take any suggestions.

[theprolo]

Is it port forwarded properly?