How to troubleshoot kenmore kitchen waste disposal?

Why is the waste disposal not letting water out by gravity action. It does flush the water out when turn on but not when it is idle (Off). It is a new kenmore waste disposal. it has been used about six times with solids and water and yes it is hooked up to the dishwasher.

the drain is clear, the outlet from the waste disposal is open.
the water just does not drain out of the waste disposal and yes, the main drain is lower then the waste disposal.

Samuel Andrade
May 2007