NFA stopped when opening graph without Exceed X Window serve

I downloaded and install NFA 4020 build in RedHat Linux 7.2. Sorry, it not required OS version; it's a box with Tivoli Netview installed with right to snmp query to other routers and switches.

Everything seems working fine after the installation, and added several routers in. But the NFA service stopped, when I close the Exceed X-window server from my installation PC. To look into the problem, I restart the netflowanalyzer service without running Exceed in my PC. I can open the NFA website, and browser through the device tree. When I clicked at one of the interfaces in a router, my browser returned no page found, and the nfa service stopped, but mySQL database is still running. I had to stop the mySQL, and restart NFA service. This time, I opened the browser to the NFA website, then open Exceed in my PC; I then clicked at the interface of one route, and able to open the page with graph displayed.

Thanks!