If the report size s larger then download the report insted f opening the report page

Dear all,

I am using vs2012 and creating reports using crystal reports in my web application.

Now the issue is ,

when I am opening crystal report,It will open up to 15 pages without any issues.But the reprt exceeds more than 15 pages ,It will show blank pages.Now my requirement is,If the report exceeds more than 15 pages then ,Instead of opening report page client need to download report for viewing the report.How can I do this? I am not getting any idea ow to do this part?

Again ,If the report size s  larger then client need a facility  to download the report insted f opening the report page

Now the report is opening with the code below

Protected Sub LnkShowReport_Click

Page.ClientScript.RegisterStartupScript(Me.GetType(), "popup", "ShowPopupReport();", True)




function ShowPopupReport()
{
    var w = 825, h = 700;
    var left = (screen.width / 2) - (w / 2);
    var top = (screen.height / 2) - (h / 2);
    var childWin = window.open("Reports.aspx");
 }



  	ElseIf Me.Title = "Daily Activity Reports_" Then
            If Not Page.IsPostBack Then
                Dim myConnectionInfo As ConnectionInfo = New ConnectionInfo()
                myConnectionInfo.ServerName = "123"
                myConnectionInfo.DatabaseName = 1
                myConnectionInfo.UserID = "2"
                myConnectionInfo.Password = "3"
                Dim ReportPath As String = Server.MapPath(reportname)
                dailyreportViewer.ReportSource = ReportPath
                dailyreportViewer.DisplayToolbar = True
                dailyreportViewer.SeparatePages = False
                dailyreportViewer.HasPageNavigationButtons = False
                dailyreportViewer.HasGotoPageButton = False

                Dim field1 As ParameterField = Me.dailyreportViewer.ParameterFieldInfo(0)
                Dim field2 As ParameterField = Me.dailyreportViewer.ParameterFieldInfo(1)
                Dim val1 As New ParameterDiscreteValue()
                Dim val2 As New ParameterDiscreteValue()
               

       
                val1.Value = "aa"
                val2.Value = "Report_"

                field1.CurrentValues.Add(val1)
                field2.CurrentValues.Add(val2)
               
                SetDBLogonForReport(myConnectionInfo)
            End If