asp.net（VB）将PPT转化为HTML格式

这是我的代码，大家看一下什么错     
        Dim appPPT As PowerPoint.Application
        Dim ppt As PowerPoint.Presentation
        Dim strFileName As String
        strFileName = "F:/JPing/第八章 2偏导数.ppt"
        appPPT = New PowerPoint.Application
        ppt = appPPT.Presentations.Open(strFileName)
        ppt.SaveAs("F:/JPing/第八章 2偏导数.ppt")
        ppt.Close()
        appPPT.Quit()

错误提示是这样的：Presentations (unknown member) : Invalid request.  The PowerPoint Frame window does not exist.

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转得还真有才......

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引用

转得还真有才......

你要是可以教我，随便你怎么鄙视啊...