Entity Framework 5.0 inheritance with multiple assemblies

I'm using Entity Framework 5.0 with code-first approach plus inheritance for my business objects represented by Table Per Hierarchy.

I'd like to have the following structure:

//Assembly 'DataAccess'    
public class MyDbContext : DbContext
{
    DbSet<AbstractClass> CommonObjects.AbstractClasses { get; set; }
}

//Assembly 'CommonObjects'  
public abstract class AbstractClass
{
    //implementation
}

//Assembly 'DerivedObjects'   
public class DerivedClass : AbstractClass
{
    //implementation
}

During runtime, when trying to access the DbContext the first time, the compiler throws an InvalidOperationException saying:

The abstract type 'CommonObjects.AbstractClass' has no mapped descendents and so cannot be mapped. Either remove 'CommonObjects.AbstractClass' from the model or add one or more types deriving from 'CommonObjects.AbstractClass' to the model.

Is this scenario even possible? If yes, what am I doing wrong?

Thanks for your answers in advance.

Ben

Additional information:

Maybe I should be a bit more specific:

I got one assembly containing my abstract business objects (only abstractions). The concrete implementations (containing the logic) are kept in the responsible assemblies, as their logic depends upon other classes within that assembly. The issue is, I want to be able to store those conrete implementations in the persistance layer as well. But for that purpose, EF had to know those types in order to enable the mapping. But I dont want to make the persistance layer depend on my business logic layer - only the abstractions.

That's why I tried to add the derived objects to the DbContext directly from the Business Object Layer.

Example:

AbstractClass derivedClass = new DerivedClass();
MyDbContext.AbstractClasses.Add(derivedClass); 

But then the exception above is being thrown. I just can't figure out a good structure to achieve this.