My Simpson eziset 500 dryer keeps cutting out since I attached the air outlet hose?

I had to do this because the laundry kept getting sweaty and dusty so i attached the outlet hose which coils up to an opening in the ceiling and hot air escapes out the roof, but the dryer keeps shutting off and needs restart by pressing the red reset button inside the door - why is this happening? Is it overheating and hot air not escaping for some reason? The outlet hose seems fitted perfectly?

dryed out, December 2009