Unable to cast object of type 'System.Data.Entity.DbSet`1[ModelName]' to type 'System.Data.Entity.DbSet'

My Entityframework context :

public class MyContext : DbContext
{
    public DbSet<Company> Companies { get; set; }
    public DbSet<Contact> Contacts { get; set; }
    public DbSet<Event> Events { get; set; }        
}

My method to add objects :

    public void AddObject(DbContext context, Type t, object object_to_add)
    {           

            PropertyInfo context_property = context.GetType().GetProperties().Where(p => typeof(IEnumerable).IsAssignableFrom(p.PropertyType)
                                          && p.PropertyType.GenericTypeArguments.Any()
                                          && p.PropertyType.GenericTypeArguments.First() == t)
                                         .Single();

            DbSet db_set = (DbSet)context_property.GetMethod.Invoke(context, null);

            db_set.Add(object_to_add);
    }

But the code crashes when I try to cast a DbSet<> to DbSet,

I'm using reflection because I receive DTO objects that I map to an existing model(via reflection as well), I don't want to code an add method for each new model (I have like 40 and the list is exponentially growing)

Blockquote

Any solution?