Can't close an open excel application from VB

[fred43200]

I'm having problems closing my excel application after using range and sort.
Here is a snippet of my code:

Set xApp = New Excel.Application
Set xBook = xApp.Workbooks.Open(filename)
Set xSheet = xBook.ActiveSheet

xSheet.Range("A12:I300).Sort(Columns("I"))

xBook.SaveAs OutPutFilename

xBook.Close True, OutPutFilename

xApp.quit
Set xSheet = Nothing
Set xBook = Nothing
Set xApp = Nothing

After this code executes I can open task manager and see that Excel is still open. Any help would be greatly appreciated. Thanks!