向下转换报错

bool operator==(IComponent &l , IComponent &r)
{
ComponentBase *cl = dynamic_cast<ComponentBase*>(&l);
ComponentBase *cr = dynamic_cast<ComponentBase*>(&r);
return cl->m_CompNo == cr->m_CompNo;
}
IComponent是ComponentBase的虚基类，这个函数能通过编译，但是运行时报：
This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.
错误，为什么？

或者这样写，也报错
bool operator==(IComponent &l , IComponent &r)
{
ComponentBase &cl = dynamic_cast<ComponentBase&>(l);
ComponentBase &cr = dynamic_cast<ComponentBase&>(r);
return cl.m_CompNo == cr.m_CompNo;
}