If a vacuum cleaner fails to suck anything up the hose it's because there's a blockage in the airway or air is entering the airway where it should not - a split in the hose for instance.
If you can remove the hose and cover the inlet with your hand you should hear the pitch of the motor increase as it runs faster.
Do the same thing with the hose connected - you should hear a similar change of pitch - if you don't then examine the hose for leaks or blockages - examine it anyway - check any internal filters.
Zoltan
September 2014