Desktop Laucher Skill display problem


How to enable the mycroft-skills service to use a display and to launch a program?

My log in mycroft-skills.log:

2017-07-28 20:05:42,487 - Skills - DEBUG - {“type”: “recognizer_loop:utterance”, “data”: {“lang”: “en-US”, “session”: “01b744c2-8ccd-40e7-a3fd-863d579c0bc6”, “utterances”: [“launch firefox”]}, “context”: null}
2017-07-28 20:05:42,490 - Skills - DEBUG - {“type”: “DesktopLauncherSkill:LaunchDesktopApplicationIntent”, “data”: {“confidence”: 1.0, “target”: null, “LaunchKeyword”: “launch”, “intent_type”: “DesktopLauncherSkill:LaunchDesktopApplicationIntent”, “Application”: “firefox”, “utterance”: “launch firefox”}, “context”: {“target”: null}}
Error: GDK_BACKEND does not match available displays

What I did before:

  1. I added export DISPLAY in mycroft user’s .profile
  2. Installed xfvb
  3. Login as mycroft user

Until now, no success.

Could you help me?