NAV 2013 RTC

I a facing a big problem in Nav 2013 Client System when I am open NAV Client in User’s System
then error is

Microsoft Dynamics NAV

The Service Principal Name (Delegation) configuration has been set
incorrectly. Server connect URL:
“net.tcp://Server ip:port/Instance Name/Service”. SPN Identity:
"DynamicsNAV/Server IP:Port"Authentication failed on the remote side (the stream might still be
available for additional authentication attempts).


error is display in both when I am open through IP or Server Name.

Please Help…