The Visual Studio 2008 Entity Data Model (EDM) requires that all primary keys are NOT Nullable, and will fail to generate an EDM if any are nullable. Thus ensure any tables to be used are defined as not nullable in the Progress database schema before attempting to generate an EDM.

It seems that, by default, several Primary Keys (PKs) in the isports database allows <NULL> values. It seems somewhat nonsensical - that a unique key used, specifically, to identify a row in a table can be allowed to be <NULL>.

This issue is best addressed directly in the database schema, by redefining those PKs that allow <NULL> so as not to allow <NULL>. Progress does not seem to talk in terms of <NULL>, instead using the term "Mandatory"

The following section will provide more specific details about how to ensure Progress PKs are not nullable: