This could be caused because port 8100 is currently blocked on the Detection server. If you perform a netstat -ano inside a Command (CMD) prompt window you should see port 8100 in a listening status.
TCP 0.0.0.0:8100 0.0.0.0:0 LISTENING 1212
NOTE: You may use netstat -ano > C:\netstat.txt to output the results to a text file.
Check and verify Windows Firewall is either disabled or an exception is added for port 8100. You can also use telnet to verify the connection from Enforce to the Detection server and make sure you can connect to it.
telnet <detection server dns name or IP> 8100
Enforce server communicates to all detection servers over port 8100.
NOTE: Enforce and Detection server services may need to be restarted in order to reestablished communication with the Detection server.