No suction through hose in upright position

I get no suction from the hose. I've checked every part/area for a blockage and everything is clear. I've changed my Post Filter and emptied the clear bin and even looked to see if the internals were clear. When I have the canister off, the suction on the right side tube is very strong, but when I put the canister back on, there is very weak suction through the hose. There is still suction when I vacuum, just not through the hose when it's in the upright position.