Error Creating Directory And Saving Excel Workbook On Vista?

I have a VB.net applications that runs on XP and creates a directory and creates an Excell workbook and saves it. But when I do the same in Vista , when it tries to create a directory to save the excel workbook, it gives me an error that the directory does not exist. If I create the directory manually, it still gives me the same error. Is there a COM call for office 2007 on Vista other than worksheet.SaveAs(FileName:=path). All else works on Vista apart from creating a directory and Saving Excell Worksheet.

Public Function createDirectory(ByVal path As String) As String
Dim new_path As String
Try

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