~You are probably doing all you should.. well it's pretty obvious so I assume you are
The chat feature's ability to work depends on many things, including firewalls, whether the other host wants to chat, whether they are anywhere near their computer when you instigate a chat, what the trafic is like on the Limewire (gnutella) network, etc etc..
If you are very lucky you will get to chat, but more often than not you will click chat with host and nothing will happen. Occasionally a dialogue box will appear, and you will type a short message, and before you have sent it you will see: "Host unavailable" ... sometimes things get better, but at the moment, I'm afraid not much
We are told improvements are in the pipeline
If you're lucky.... break out the fine wine