You just gave 30 compressions to an unconscious choking adult. you checked the mouth and didn't see any obvious object that could be swept clear. you opened the airway and attempted a breath. no air went in. what should you do next?

I would reposition the airway and attempt another breath. I would want to make sure that the airway is open enough that the air is going in and do another check to make sure that there were no obstructions when I repositioned the airway.