accesing my radio station from the net

[beedee]

i know my ip and port number etc. im registered with shoutcast etc..my server is running theres is a source...all is good! but when i put my http://IP:PORTNO/listen.pls it wont connect.....i think its to do with my router but that shouldnt matter coz the ports are right but maybe it messes up the IP address?