I have a modelF5914-900 steamvac

Question

I have a modelF5914-900 steamvac cleaner.serial #0704 0011 4711 I cleaned the carpets in my house and then started to do the stairs with the stair attachment. I got down to the last four stairs and the solution would no longer come out. I checked the tank and hose connection and tried priming the pump per the instruction manual. nothing worked. Could you make a suggestion as to what the problem could be? Thank You