https下 ie 无法下载文件

Question

 Private Sub DownLoadPDF(ByVal filepath As String)
        Dim response As System.Web.HttpResponse = System.Web.HttpContext.Current.Response
        Dim pdfFileName As String = "Exported.pdf"
        If (File.Exists(filepath)) Then
            Dim downloadBytes() As Byte = File.ReadAllBytes(filepath)
            pdfFileName = Path.GetFileName(filepath)
            'File.Delete(Me.pdfFilePath)            response.Clear()
            response.AddHeader("Content-Type", "binary/octet-stream")
            'response.AddHeader("Expires", "0")
            'response.AddHeader("Pragma", "public")
      
            'response.AddHeader("Pragma", "no-cache")
            'response.AddHeader("Cache-Control", "must-revalidate, post-check=0, pre-check=0")
            'response.AddHeader("Cache-Control", "public")            If (System.Web.HttpContext.Current.Request.Browser.Browser.ToLower() = "ie") Then
                pdfFileName = HttpUtility.UrlEncode(pdfFileName, System.Text.Encoding.UTF8)
            End If
            response.AddHeader("Content-Disposition", ("attachment; filename=" _
            + (pdfFileName + ("; size=" + downloadBytes.Length.ToString))))
            response.Flush()
            response.BinaryWrite(downloadBytes)
            response.Flush()
            response.End()
    
        End If
    End Sub网上说加上注释的那段就可以，可我始终没有成功（在pageload事件中掉改方法没有问题，但是在按钮的click事件中就会出现下载aspx页面，并提示找不到）
哪位高手指点下啊