Dishwsher won't drain

The water in my dishwasher will not drain. I can take a shop vac and drain it from the hose that connects to the garbage disposal to the dishwasher and it empties it. so there is no clog in the hose. can you help me figure out what it could be. thankyou Marilee

Here is the parts breakdown
Replacement parts for FRIGIDAIRE FDBB540DB1 Frigidaire/dishwasher | AppliancePartsPros.com

Here is the tech sheet
http://manuals.frigidaire.com/prodinfo_pdf/Kinston/154457601.pdf

Check to see if the drain motor (Item 60 in Section 4) is getting 120 volts when it should.
If it is and it is not running it is toast.