Navigate2 compare with Navigate

CWebBrowser2 ctrl provide two method to link a web page:
Navigate2(VARIANT* URL, VARIANT* Flags, VARIANT* TargetFrameName, VARIANT* PostData, VARIANT* Headers)
Navigate(LPCTSTR URL, VARIANT* Flags, VARIANT* TargetFrameName, VARIANT* PostData, VARIANT* Headers)

My requirement is very simple, give a link: such as www.sina.com, navigate to web page.
At first, I use method Navigate because it is easy to use.
But sometimes I find that it get a error page while I can link the web page with other browser.

After a long time research, I can not find a good solution, then I found the method Navigate2. I wrote a method to rope it as follow:

<!--<br><br>Code highlighting produced by Actipro CodeHighlighter (freeware)<br>http://www.CodeHighlighter.com/<br><br>--> 1 void Navigate2(CString szHtmlUrl)
 2 {
 3     try
 4     {
 5         VARIANT vFlags = {VT_I4, navNoReadFromCache};
 6         VARIANT vUrl; 
 7         VariantInit(&vUrl);
 8         BSTR bstrUrl = szHtmlUrl.AllocSysString();
 9         vUrl.vt = VT_BSTR;
10         vUrl.bstrVal = bstrUrl;
11         m_web.Navigate2(&vUrl, &vFlags, NULL, NULL, NULL);// refresh top browser's content
12         g_Logger.Add(LOGLEVEL_FYI, _T("Navigate2TopBanner, Top link Url: %s"), szHtmlUrl);
13         ::SysFreeString(bstrUrl);
14     }
15     catch(){}
16 }

It works well....

Compare the implements:

<!--<br><br>Code highlighting produced by Actipro CodeHighlighter (freeware)<br>http://www.CodeHighlighter.com/<br><br>-->1 void CWebBrowser2::Navigate(LPCTSTR URL, VARIANT* Flags, VARIANT* TargetFrameName, VARIANT* PostData, VARIANT* Headers)
2 {
3     static BYTE parms[] =
4         VTS_BSTR VTS_PVARIANT VTS_PVARIANT VTS_PVARIANT VTS_PVARIANT;
5     InvokeHelper(0x68, DISPATCH_METHOD, VT_EMPTY, NULL, parms,
6          URL, Flags, TargetFrameName, PostData, Headers);
7 }

<!--<br><br>Code highlighting produced by Actipro CodeHighlighter (freeware)<br>http://www.CodeHighlighter.com/<br><br>-->1 void CWebBrowser2::Navigate2(VARIANT* URL, VARIANT* Flags, VARIANT* TargetFrameName, VARIANT* PostData, VARIANT* Headers)
2 {
3     static BYTE parms[] =
4         VTS_PVARIANT VTS_PVARIANT VTS_PVARIANT VTS_PVARIANT VTS_PVARIANT;
5     InvokeHelper(0x1f4, DISPATCH_METHOD, VT_EMPTY, NULL, parms,
6          URL, Flags, TargetFrameName, PostData, Headers);
7 }

I find that they invoked different  dwDispID  of  InvokeHelper, get the explain from MSDN:

Parameters

dwDispID
Identifies the method or property to be invoked.

Who can tell me what's the differents of 0x1f4 between 0x68?