主题：我在浏览器中打开excel 连续打开一直提示文件打开需要关闭!

我用这个代码执行,但是连续执行一直提示文件打开需要关闭! 我加了关闭进程也不行,加了判断文件是否打开执行关闭后 也不行,还是一直提示! 应该怎么做比较好?

Dim wbr As WinForm.WebBrowser = e.Form.Controls("WebBrowser1")
Dim tmp As String = ProjectPath & "Attachments\资料卡.xls"
Dim rpt As String = ProjectPath & "Reports\资料卡.pdf"
Dim Book As New XLS.Book(tmp)
Book.Build()
Book.SaveToPDF(rpt) '保存为pdf文件
wbr.AddRess = rpt