Daf as tronic fault?

Hi, I have a 2006 Daf cf 85 with a 16 speed as tronic box, it has started coming up with transmission fault on the dash and won't go into auto mode, the fault goes away after a few kilometres and everything is fine, then it comes back and I only have manual mode again, my cruse control has stopped working at the same time as this issue as we'll.

Any ideas?