Can't send or receive files with KMess
 

When I try to send a file with KMess (to an MSN Messenger) there is a box saying Confirm your IP. I can use 192.168.0.100 or get one from whatismyip.com. Either way it just does nothing and after a while the MSN Messenger says the transfer failed. I can't receive files either. KMess says "A connection could not be made."
I have tried it with two different Windows computers. They are both connected to mine with a router. I haven't tried this with any computer outside my house yet so this could have something to do with it... but it works fine with MSN Messenger....