大神求助，VC中利用webbrowser获取网页iframe框架内元素问题

[sinat_30784251]

我要操作的网页源代码中有这么一段代码</div>
<iframe src="http://admin.erya100.com/login/loginManage!toStudent?servicename=tsk_student&serviceurl=http://fjsdxy.tsk.erya100.com/student/toindex.jsp&schoolid=0000996&logouturl=http://fjsdxy.tsk.erya100.com/&t=20121116" height="356" width="476" frameborder="0"
scrolling="no" llowtransparency="true" frameborder="0"></iframe>
现在我要获取iframe中的一个控件，采用如下代码

IDispatch *pDispatch = C控制网页元素Dlg::m_web.get_Document();
IHTMLDocument2 *pDoc;
HRESULT hr = pDispatch->QueryInterface(IID_IHTMLDocument2, (void**)&pDoc);
if (hr != S_OK)
{
pDoc->Release();
pDispatch->Release();
return;
}
IHTMLFramesCollection2 *pFrame=NULL;
hr=pDoc->get_frames(&pFrame);
if (hr!=S_OK)
{
MessageBox(TEXT("失败1"));
return;
}
long count=0;
pFrame->get_length(&count);
if (count == 0)
{
MessageBox(TEXT("失败2"));
return;
}
for (int j = 0; j < count; j++)
{
VARIANT varIndex, varDispatch;
varIndex.vt = VT_I4;
varIndex.lVal = j;
VariantInit(&varDispatch);
pFrame->item(&varIndex, &varDispatch);
IDispatch *pDispatch2=NULL;
pDispatch2 = (IDispatch*)varDispatch.pdispVal;
IHTMLDocument2 *pDoc2 = NULL;
HRESULT hr = pDispatch2->QueryInterface(IID_IHTMLDocument2, (void**)&pDoc2);
if (hr != S_OK)
{
MessageBox(TEXT("失败3"));
continue;
}
IHTMLElementCollection *pColl = NULL;
long nElement;
pDoc2->get_all(&pColl);
pColl->get_length(&nElement);
for (int i = 0; i < nElement; i++)
{
IDispatch *pDispatch3;
VARIANT varIndex, var;
varIndex.vt = VT_I4;
varIndex.lVal = i;
VariantInit(&var);
pColl->item(varIndex, var, &pDispatch3);
if((hr == S_OK) && (pDispatch3!= NULL))
{
IHTMLElement *pElem = NULL;
hr = pDispatch3->QueryInterface(IID_IHTMLElement, (void**)&pElem);
if ((hr == S_OK) && (pElem != NULL))
{
VARIANT attr;
VariantInit(&attr);
BSTR bstrtemp;
bstrtemp = SysAllocString(L"name");
hr = pElem->getAttribute(bstrtemp, 1, &attr);
bstrtemp = attr.bstrVal;
CString val = bstrtemp;
CString strValue = TEXT("登录");
if (val == strValue)
{
MessageBox(TEXT("找到登录控件"));
pElem->click();
pElem->Release();
pDispatch3->Release();
pDispatch2->Release();
pDispatch->Release();
}
if (val!=TEXT(""))
MessageBox(val);
pElem->Release();
}

}
pDispatch3->Release();
}
pDispatch2->Release();
}
pDispatch->Release();

每次执行都提示失败3，应该就是这句代码的问题HRESULT hr = pDispatch2->QueryInterface(IID_IHTMLDocument2, (void**)&pDoc2);
请大家帮我看看我的思路是不是出问题了？麻烦大家给我说说正确的操作方法是什么，如果有源代码我感激不尽！

[sinat_30784251]

顶一个！！！！