Launching App from Cron Job

I’ve got a working application that uses Matrix Creator. I want it to autostart - but can’t seem to get it working. I’ve got a shell script that works fine from the command line - but when I try to run this script from cron at reboot I get the error:

MATRIX device has not been detected
Bus did not load

If ssh in and retype the shell script it works fine. I thought it might be a path problem maybe? But tried adding all the existing path explicitly - but same problem. I think it must be about running the job from a different context - but cant figure it out. Has anyone any ideas?

Thanks

Stephen