MSScriptControl AddObject Problem

Hi,
 
I'm wanting to use the MSScriptControl from C++ (Visual Studio 2012). When I call the AddObject in runtime I get a "Specified Cast Is Invalid" error.
 
I have this is my AssemblyInfo.cpp:

[assembly:ComVisible(true)];

 
This is my BasicCommands.h:

namespace BasicCommands
{
	ref class BasicCommandsClass
	{
		//speak a phrase
	public:
		void SpeakPhrase(String^ phrase)
		{
			SpeechSynthesis::SpeakPhrase(phrase);
		}
		
	
 
		void RunScript(String^ script)
		{
			MSScriptControl::ScriptControlClass^ pScriptControl=gcnew MSScriptControl::ScriptControlClass();
			pScriptControl->Language = "vbscript";
			pScriptControl->AllowUI = true;
			pScriptControl->AddObject("MyCommands",this,true);
			pScriptControl->ExecuteStatement(script);
		}
	};
}

 
The AddObject should be adding the SpeakPhrase command so I can call it from my vbscript.
 
Any idea why it's not working?
 
Cheers,
Mike.