Can't create parent key
Sorry, newbie here. We've been creating tables and parent/child keys to start, but suddenly, we are no longer able to create a parent key. No matter in a table that already exists, or in a new testing table, as soon as we create and designate a parent key (__pkProductID) and try to drag it in the relationship graph, it immediately sees it as a child (when dragging, the triangle starts from the 'left hand side'.) All other parent keys we have created are fine and show the proper one-to-many relationship.
I'm sure it is something simple, but...help!