eclipse - Selenium throwing 'no display specified' error when one exists -

i have script starts selenium server (if 1 not running) , runs acceptance tests in codeception (with firefox version 27, compatible our selenium 2.42.2). if go onto server (using vnc), script runs , executes properly, i'm using eclipse rtc plugin, , it's set can make build request, run script on server.

for reason fails error (or variant of it):

15:42:26.125 warn - exception: unable connect host 127.0.0.1 on port 7055 after 45000 ms. firefox console output: error: no display specified error: no display specified 

on server, if manually export display, still fails rtc. far can tell, there's nothing special in build rules cause this. it because vnc happens gui, , can't find display terminal?

this means there not graphical interface available user(as use ssh connect), suggest use xvfb