I don't understand why i get an InvalidCastException when calling
Marshall:ReleaseComObject() in this code :

RCW   -----> CCW ----> .NET Control
 p1                p2                p3

void Proc( IUnknown* p2 )
{
   Object* p1 = Marshal::GetObjectForIUnknown(p2);   //  p2 is a CCW on a
.NET Control

   try
   {
         .....
   }
   __finally
   {
       Marshal::ReleaseComObject(p1); //InvalidCastException here
   }

}

Remark : There is no exception if p2 is a normal COM object (not a CCW on a
.NET Control)