主题：打印中遇到的问题

用如下代码，控制AAA模板打印：

Dim Book As New XLS.Book(ProjectPath & "Attachments\AAA.xls")

Dim fl As String = ProjectPath & "Reports\\AAA.xls"

Book.Build()

Book.Save(fl)

Dim App As New MSExcel.Application

Dim Wb As MSExcel.WorkBook = App.WorkBooks.Open(fl)

Dim Ws As MSExcel.WorkSheet = Wb.WorkSheets(1)

App.Visible = True

ShowAppWindow("\AAA,2)

Ws.PrintPreview

App.Quit

问题：

      窗口下显示打印后退出时，有的在电子表格下询问是否保存AAA，有的不询问，直接退出，请问要保证有询问状态，如何修改？