Why isn't my Bissell carpet cleaner picking up water?
Why is my carpet shampooer lost suction?
A possible cause might be that the tank is not properly seated. To assure the tank is seated properly, pick it up and re-seat is so it sits snugly on the unit. If this doesn't fix the problem, make sure the tank is assembled properly. To make sure they are both latched properly, pick the tank up by its handle.