tricky COM inheritance question (resolved)

I am writing a COM object that has one base class that the rest of the classes implement.

As an example, let's say I have an object IMessage that has one empty subroutine, Show. Then I have two classes SnailMail and Email that implement IMessage.

Is it possible now to add another class, let say "Fax", to the COM object without breaking the clients?

I tried to do it like this:
dim clsMessage as IMessage

set clsMessage = CreateObject("MessageObject.SnailMail")
clsMessage.Show

This works great, but I have to recompile each time I add a new class to the MessageObject COM object.

It was my impression that, by using Automation, e.g. CreateObject() syntax, I would be able to update the COM server without any problem.

What am I missing, or is this impossible? When I try to instantiate the class after I change the COM server, I get a "Type Mismatch" error.

Thanks in advance,

Nevermind, I figured it out.

If I make a type separate libary and use that interface to implement in the classes in my COM Object, then everything works!

I wish I could say I knew why...But, getting it to work is half the battle.