主题：浏览器打开EXCEL报表,如何关闭

Dim FName As String = ProjectPath & "Reports\报价表.xls"

If FileSys.FileExists(FName) Then

    Try

        Dim f As New System.IO.FileStream(FName,IO.FileMode.Open,IO.FileAccess.Read,IO.FileShare.None)

        f.Dispose()

    Catch ex As Exception

        MessageBox.Show("报价单打开中,请先关闭!","提示!")

        Dim App As New MSExcel.Application

        Dim Book1 As MSExcel.Workbook = App.Workbooks.Open(ProjectPath & "Reports\报价表.xls")

        App.Visible = True

        Book1.Saved=True

        Book1.Close()

        App.Quit()

        e.Form.Controls("WebBrowser1").AddRess = ""

    End Try

End If

Dim tmp As String = ProjectPath & "Attachments\报价表.xls"

Dim rpt As String = ProjectPath & "Reports\报价表.xls"

Dim Book As New XLS.Book(tmp)

Dim dr As DataRow

Dim r As Row  = Tables("订单主表").Current

If r IsNot Nothing Then

    dr = DataTables("客户档案").Find("客户编号='" & r("客户编号") & "'")

    If dr IsNot Nothing Then

        Book.Marks.Add("联系人",dr("联系人"))

        Book.Marks.Add("联系电话",dr("联系手机"))

    End If

End If

Book.Build()

Book.Save(rpt)

e.Form.Controls("WebBrowser1").AddRess = rpt

  我写了这个代码,但是还是提示报表打开中,如何关闭?