> I am sure it is because of the protected keyword on the constructors for B
> and C but I do not understand the underlying reason.

> Can anyone explain it?

> Thanks in advance!

> abstract class A
> {
>  public enum AType {BType, CType};
>  protected A()
>  {
>  }
>  public static A CreateAFactory(AType typ)
>  {
>    switch(typ)
>    {
>    case AType.BType:
>      return new B();
>    case AType.CType:
>      return new C();
>    }
>  }
> }
> class B : A
> {
>  protected B() : base()
>  {
>  }
> }
> class C : A
> {
>  protected C() : base()
>  {
>  }
> }