Instant messaging

Hello Gurus,

I am trying to configure collaboration features on the Portal. the first thing I did was, I got the Collaboration launch pad in the tool area of the Portal. I then added two contacts and tried sending them instant messages. But I just see a blank chat window, after writing a message and hitting send button. The person at the other end is also not receiving any messages.

What else needs to be configured for the Instant messaging to work properly?

As always, points galore for the right and helpful answers.

Thanks

~LB