Fire an event with an Interface pointer

Is it possible to fire an event with an interface pointer as an argument?

Say for instance I have an ATL object called CObj, this object fires an
event, I want a parameter of this event to be an interface pointer to the
object itself.

in the idl file I have created the following;

dispinterface _IObjEvents
{
 properties:
 methods:
 [id(1), helpstring("method event")] HRESULT Event([in] IObj* pobj);
};

Then within the object I fire the event in the following manner;

HRESULT CSomeObj::SomeFunc() {
  Fire_Event(this);
  // ---- or maybe ---- Fire_Event(CComPtr<IObj>(this));
  return S_OK;
}

When I look at the generated _CP.h file it doesn't seem that the generated
code is correct, it generated the following;

HRESULT Fire_Event( IObj * pobj)
{
 ...
 ...
    CComVariant avarParams[1];
    avarParams[0] = pobj;
    CComVariant varResult;

 ...
 ...
}

When I run this code using a VB client the program crashes on the event
handler, it states that the object in empty. I know this must be possible,
any help would be greatly appreciated