What could be wrong if pool will not vacumm manualy?

(1) The vacuum hose has a leak some where.

(2) The leaf basket behind the skimmer is over full.

(3) The Hair filter basket in front of the pump is full.

(4) The filter needs cleaning or backwashing.

(5) The way the valves are adjusted is not allowing for maximum suction through the port that is being used for the vacuum hose.

(6) The impeller of the pump is broken down or clogged.