I can not get the Kirby vacuum to **** up the foam...

Question

I have borrowed a Kirby from a friend who has no idea how to run it herself. Well, I looked up the instructions online and got it put together and got it to lay out the foam alright. ( Except for the fact that it took a lot for a small area ) Now, I can not seem to get the shampoo to **** back up into the tray. I have turned the nob on top of the shampoo tank to off and still nothing. I have lowered the setting all the way down and still nothing!! Does anyone know what I am doing wrong??? Please help me!!