No liquid discharge. The pump is not primed. Prime it from the outlet side by keeping the outlet air vent open until liquid comes out the vent. The rotating unit is turning in the wrong direction.
Valves are closed or there is an obstruction in the inlet or outlet line.
Check that the flange gaskets have their center cut out. The end of the inlet pipe is not submerged. You can either increase the length of the inlet pipe into the liquid level or raise the level in the tank. The foot valve is stuck. A strainer or filter is clogged.