Why wouldn't airbags deploy when hitting a deep ditch head on and rolling your car doing 45 mph?

Why wouldn't airbags deploy when hitting a deep ditch head on and rolling your car doing 45 mph?
The air bags should definetely have deployed at that speed. You should contact the car manufacutrer right away so they can look at it. It is possible however, to miss the sensors that tell the air bags to deploy. They are set back from the bumper and grill enough to avoid going off in a low speed colision but if you hit the ditch in just a certain way that it didn't push the bumper back enough to contact the sensors, they wouldn't go off. Still, I would say the fuse was blown on the airbag circuit or the air chamber was empty already or some other malfunction but still, contact the manufacturer. I'd call them instead of the garage that sold you the car in the first place so you get a second opinion.