VB.net InternetExplorer HtmlDocument

Question

有人能帮助我吗？我是VB.net的新手，并尝试编写一个非常简单的代码来操纵一个网站。但是，我一直在

  

“发生了'System.InvalidCastException'类型的未处理异常   在Defer All.exe ....无法转换类型的COM对象   'System .__ ComObject'到接口类型'mshtml.HTMLDocument'。这个   操作失败，因为QueryInterface调用COM组件   对于与IID'....）的接口。“

        Dim IE As InternetExplorer
        Dim HTMLDoc As HtmlDocument
        Dim oHTML_Element As mshtml.IHTMLElement
        IE = new InternetExplorer
        IE.Navigate("http://www.mediafire.com/")
        Do Until IE.ReadyState = 4
        Loop
        Loop Until Not IE.Busy
        ' ERROR on the following line
        HTMLDoc = IE.Document
        ' I tried making HTMLDoc as object. It passed the above line, but failed the next line due to no GetElementsByTagName method
        For Each oHTML_Element In HTMLDoc.GetElementsByTagName("input")
          '....................
        Next

Answer 1

...变化

Dim IE As InternetExplorer
Dim HTMLDoc As HtmlDocument
'                    ^---------------------------this thing to,
                                                 mshtml.IHTMLDocument
Dim oHTML_Element As mshtml.IHTMLElement