ActiveX控件多线程回调javascript方法的问题

参照http://topic.csdn.net/u/20070212/20/1011ad32-1ce7-416d-9e6c-cffca7a100fe.html?seed=1066340289我试着写了一个OCX控件,主要代码如下:
//重载SetSite
STDMETHODIMP CAXClass::SetSite(IUnknown *pUnkSite)
{
CComPtr <IServiceProvider> pSP;
CComPtr <IDispatch>  spDisp;

HRESULT  hr  =  pUnkSite-> QueryInterface(&pSP);
pSP-> QueryService(IID_IWebBrowserApp,  IID_IWebBrowser2,  (LPVOID*)&m_pWebBr); //m_pWebBr成员变量，定义 CComQIPtr <IWebBrowser2, &IID_IWebBrowser2> m_pWebBr;

//m_pWebBr-> get_Document((IDispatch**)&m_pDoc);
//hr = m_pDoc->get_Script(&spDisp);

::CoMarshalInterThreadInterfaceInStream(IID_IWebBrowser2,m_pWebBr, &m_pStream);  //m_pStream是成员变更，定义 CComPtr <IStream> m_pStream;

return S_OK;
}

//线程处理函数
UINT ThreadProc(LPVOID lpParam)
{
::CoInitializeEx(NULL,COINIT_APARTMENTTHREADED);

CComPtr <IHTMLDocument2>  spDoc;
CComPtr <IDispatch> spDisp;

char szBuf[256] = {0};

IStream * pStream = (IStream *)lpParam;

CComQIPtr <IWebBrowser2, &IID_IWebBrowser2>  pWebBr;

::CoGetInterfaceAndReleaseStream(pStream, IID_IWebBrowser2, (void**)&pWebBr);

HRESULT hr = pWebBr-&