EntityServerException on a query with a subquery on an inherited entity

companyGroupId

Hi,

I am getting an error during the execution of a query on a model where exist TPH inheritance.

EntityServerException: Une expression de type 'System.Data.Objects.ObjectQuery`1[ConsoleApplication4.Company]' ne peut pas être utilisée pour un paramètre de type 'System.Linq.IQueryable`1[ConsoleApplication4.GamingCompany]' d'une méthode 'System.Linq.IQueryable`1[ConsoleApplication4.GamingCompany] Where[GamingCompany](System.Linq.IQueryable`1[ConsoleApplication4.GamingCompany], 
System.Linq.Expressions.Expression`1[System.Func`2[ConsoleApplication4.GamingCompany,System.Boolean]])'

My model has an entity GamingCompany which inherit from the entity Company. The model looks like this :
Here is the query         
                    from c in Customers
                    from o in c.Orders
                    let companyGroupId = (from e in GamingCompanies where (e.ID == 0) select e.CompanyGroupId).FirstOrDefault()
                    where (o.GamingCompany.CompanyGroupId == companyGroupId)
                    select c;

Now I made a model where I broke the inheritance and the modified query works.

            var q = from c in Customers
                    from o in c.Orders
                    let companyGroupId = (from e in Companies where (e.ID == 0 && e.Discriminant == 1) select e.FirstOrDefault()
                    where (o.Company.CompanyGroupId == companyGroupId)
                    select c;

What am I doing wrong ? Is it not allowed to do subquery on a inherited entity ?

Regards,

EDIT  : on the first model, if the CompanyGroup relation is on Company and not GamingCompany it's working. Unfortunatly I need it on GamingCompany ...

Edited by Walid - 29-May-2012 at 9:53am