There is a similar issue if you wish to use a PiCamera:
Picamera Use Issues
The python test script to access the picamera worked well from the start. When I integrated the picamera functionality into the skill’s init.py file, at first it didn’t work,then after some tweaking it did work, but only once!
The file /var/log/mycroft-speech-client.log and /var/log/mycroft-skill.log are very useful files to look at if your skill is not working. After some looking, I found an error dealing with a “vchiq instance”.
Having learned my lesson from past experience, I did a google search, and found that in order the access the camera, the user executing the Python program or Mycroft skill in this case needed to have a file permission to do this. In Linux most everything is a file, even a device. To access the picamera, a user needs access to a file called /dev/vchiq. So the user executing the python test script had access, but the user, called pi, executing the init.py did not. Hence the failure to take the picture at all. Following the directions from Raspberry Pi – failed to open vchiq instance [Solved] demonstrates how to change the user permissions for this file to allow access to the device. I’ve placed a pdf of this post in my github repository for this project in case the link goes stale.
You can see the full write up here(which will also provide the link to github mentioned above):