Entity Framework 6 doesn't detect inheritance

I have the following class setup

 public abstract class SearchElement
{
    public int Id { get; set; }

    public SearchElement parent { get; set; }

    public int Order { get; set; }

    public UserQuery UserQuery { get; set; }
}

public class SearchGroup : SearchElement
{
    public virtual ICollection<SearchElement> SearchObjects { get; set; }

    public bool IsAndOperator { get; set; }

    public SearchGroup()
    {
        this.SearchObjects = new List<SearchElement>();
    }
}
public abstract class SearchCondition<IContext, OutputType> : SearchElement
{
    public ComparisonTypes Comparison { get; set; }

    public string Value { get; set; }

    public abstract Expression<Func<OutputType, bool>> BuildConditionQuery(IContext context);
}
public class SearchPackage : SearchCondition<ISearchContext, ProjectParticipantQuestionnaireResponseGroup>
{
    public override System.Linq.Expressions.Expression<Func<ProjectParticipantQuestionnaireResponseGroup, bool>> BuildConditionQuery(ISearchContext context)
    {
        return this.BuildCondition<ProjectParticipantQuestionnaireResponseGroup, int>(r => r.Package.Id, int.Parse(this.Value), this.Comparison);            
    }
}

Now for some reason, when in the EntityFramework context I specify:

public DbSet<SearchElement> SearchElements { get; set; }

The SearchGroup class gets detected and the appropriate fields get created in the SearchElement table. However, the SearchPackage class does not get detected and it's fields are not created in the SearchElement table.

I can of course create a DbSet for the SearchPackage, but there are multiple similar classes (same inheritance, although some with difference values) and I don't want to create a DbSet for each of them. Does anyone has suggestions about what I can do?

For clarity: I am using Entity Framework 6.1.3 and C# 4.5.1