It can be brush, rollers or motor issue too.:---
Unplug your Dirt Devil vacuum from the wall outlet in your home.
Take the suction assembly off of the vacuum arm. Check the tube on the suction assembly to see if anything is obstructing the suction. If you find something remove it.
Check the bottom of the canister to make sure nothing is obstructing the opening of the canister.
Take the vacuum extension arm off of the control panel and raise it to eye view. Look through the extension arm and make sure that nothing is obstructing the suction inside the extension arm.
Remove the suction tube from the Dirt Devil body and check the hose for anything stuck inside.
Look through the hole where the suction hose connects with the Dirt Devil body. Make sure nothing is stuck in the hole.
Turn on your Dirt Devil and you will have suction.
If the unit is under warranty, then get it repaired by the manufacturer, instead of voiding the warranty.