This problem occurs mainly due to communication issue.
First we need to make sure whether the 'ping' and 'telnet' are functioning properly.
Try to ping from the PatrolAgent machine to rtserver machine and check whether its able to ping and telnet.
If it seems alright, then try the ping and telnet from the RTserver machine to PatrolAgent machine.
Communication should be alright from both the ends.
Once it is done, check the RTserver variable in the PatrolAgent configuration ruleset "/AgentSetup/rtserver " to confirm its connecting to correct RTserver and right port.
Also can try running the PatrolAgent with the RTserver string as below:
./PatrolAgent -p <port no> -rtserver tcp:hostname:2059
Please let us know if the problem still persists.