Users are shoing (pending) why and i am not able to chat with

Hi,

I install the wildfire software on the windows 2k3 server w/o firewall turned on. I am able to access the admin web page. I have installed exodus client on few pcs. I have added few user to each client but all client are shounf (pending) status next to user IM-ID, WHY!!! How do i fix this?