Is the garbage disposer knockout plug removed?
If the dishwasher is connected to a garbage disposer, be sure the knockout plug has been removed from the disposer inlet.
CLICK HERE for more information on removing the garbage disposer knockout plug.
CLICK HERE to watch a video on how to connect the dishwasher drain to a garbage disposer
Are there any obstructions in the drain or garbage disposer?
Check for any food or obstructions caught in the drain or the garbage disposer. Run the disposer to clear the obstruction.