Delete file by previous date with VBScript

Set shell = CreateObject("WScript.Shell")	'Set for call batch file
shell.CurrentDirectory = "c:\Testscript"		'Location batch file
Set fso = CreateObject("Scripting.FileSystemObject")
startFolder = "d:\FileBackup"		'Folder to start deleting (subfolders will also be cleaned)
OlderThanDate = replace(DateAdd("m", -1, Date),"/","")  	'Adjust as necessary
DeleteOldFiles startFolder, OlderThanDate
Function DeleteOldFiles(folderName, BeforeDate)
	Dim folder, file, fileCollection, folderCollection, subFolder	
	Set folder = fso.GetFolder(folderName)
	Set fileCollection = folder.Files
	'wscript.echo fso.GetFileName(file.Path)		'Test show file path
	For Each file In fileCollection		
		FullDate = Right("0" & Day(file.DateLastModified),2) & Right("0" & Month(file.DateLastModified),2) & Year(file.DateLastModified)		'Format date
		if FullDate = BeforeDate then
			'wscript.echo fso.GetFileName(file.Path)		'Test show file path
			fso.DeleteFile(file.Path)	' Delete previous file name			
			shell.Run "Batch file.bat"	'Can run batch file move data and log this here
		else
			shell.Run "Batch file.bat"	'Can run batch file move data and log this here
		end if
	Next	
End Function

Call c:\vbscript.vbs