i have got a error message while i jsut trying to connect to oracle9i. the error message i was getting is,

The server encountered an internal error (Io exception: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=153092352)(ERR=12505)(ERROR_STACK=(ERROR=(CODE=12505)(EMFI=4))))) that prevented it from fulfilling this request.


my database setting are

sid=cts;
user=scott;


i hope will get some solution for this problem.
Thanks
Ravi