VS 2008 : Save A File Data Using The Savefiledialog?

I was trying to export a data from the listview control into an excel format and I was able to make it successfully using a command button directly. I want to use a SaveFileDialog to export and save the content of the listview.

I searched from MSDN website and got a sample code which was originally intended for saving an image file. I tried to used it and edit the code and combine my code to export the data content. It ran successfully and attempt to export the data in an excel format but when you open the file in the path as to where you save the data, it gives you a message "Excel cannot open the file 'Filename.xlsx' because the file format or extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file." and it just leaves an empty excel file.

I read from the MSDN site that if you are using an MS Office 2007, the file extension for excel would be '.xlsx' and not 'xls'. Let me give you the two codes I tried to use. First, I used command button and was able to successfully export and save the content in an excel format but using the SaveFileDialog was not successful.I suspected that there's something wrong within this line

'oBook.SaveAs("saveFileDialog1.FileName.GetType()")' and 'Dim fs As System.IO.FileStream = CType _(saveFileDialog1.OpenFile(), System.IO.FileStream)'.

Here are the two diffrent codes I used:

'Using the command button-----successful
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

[code]....