请教哪位高手知道如何在VB程序中打开PPT2007的文档

请问谁知道怎么在VB程序中打开PPT2007的文档?
在PPT2003中可以用这样的语句:
  Set Ppt = CreateObject("PowerPoint.Application")
  Set Pst = Ppt.Presentations.Open(FileName, , , 0)
但是在Office2007下，Ppt.Presentations.Open这一句会出错？改用Ppt.Presentations.Open2007也会报错？

------解决方案--------------------
是不是没有添加引用？工程－》引用－》。。。
------解决方案--------------------
他是动态创建的,不需要引用ppt.

Dim a As New PowerPoint.Application
Dim b As PowerPoint.Presentations
a.Visible = msoTrue
Set b = a.Presentations
Dim c As PowerPoint.Presentation
Set c = b.Open("C:\阿第三方.ppt")

没看见错误.

Function Open(FileName As String, [ReadOnly As MsoTriState], [Untitled As MsoTriState], [WithWindow As MsoTriState = msoTrue]) As Presentation
你指定WithWindow=msoFalse = 0是...
我也没明白那个值..