sumon, I assume you were trying to add a "syslog" server using "Registered Servers" option in ePO correct? Did you use tcp port 6514? Is your syslog server properly configured to accept connection FROM your ePO server on that port? Are you using IP address or DNS name in the "server name" field?
Please do these basic test from your ePO server - test pinging syslog server by IP and DNS name, then use nslookup for both, telnet to syslog server on that port 6514.