Updating a report source/viewer with new filename

Question

I posted earlier about this problem but now can be more specific so thought a re-post was in order. I am trying to setup an asp.net website using .NET 2.0 and Crystal Reports 2008. Rather than having a seperate page for each possible report with a viewer on it I decided to setup a page and pass it session variables telling it what file name to set the report source to and the variables to pass to it. This worked fine in crystal reports basic (the one with visual studio).
So I have on the page CrystalViewer (CrystalReportViewer) with display page true seperate pages true and crystalRepSource (CrystalReportSource) with cache enabled and viewstate enabled as far as I know cache is required for the paging to work.
In my form code behind file i have something like:
protected void Page_Load(object sender, EventArgs e) {
CrystalRepSource.Report.FileName = SessionHandler.RunReport;
switch (report)
if (PreviousPage != null || paramHasChanged)
case @"~\CollegeReports\CR_Course_Review.rpt":
                //setup report in viewer with correct db logon
                SetupLogonInfo(CrystalRepSource);
                //add parameters
                CrystalRepSource.ReportDocument.SetParameterValue("@year", year);
                CrystalRepSource.ReportDocument.SetParameterValue("@school", school);
                CrystalRepSource.ReportDocument.SetParameterValue("@division", division);
                CrystalRepSource.ReportDocument.SetParameterValue("@progArea", progArea);
                CrystalRepSource.ReportDocument.SetParameterValue("@type", SessionHandler.record_type);
                CrystalRepSource.ReportDocument.SetParameterValue("@filterText", "School = \'" + school +
                                                        "\' Division = \'" + division
                                                        + "\' Programme Area = \'" + progArea
                                                        + "\' Record Type = \'" + SessionHandler.record_type_text + "\'");
                break;
            case @"~\CollegeReports\CR_WBL_Attendance_Sheets.rpt":
                //setup report in viewer with correct db logon
                SetupLogonInfo(CrystalRepSource);
                //add parameters
                CrystalRepSource.ReportDocument.SetParameterValue("@year", year);
                CrystalRepSource.ReportDocument.SetParameterValue("@school", school);
                CrystalRepSource.ReportDocument.SetParameterValue("@division", division);
                CrystalRepSource.ReportDocument.SetParameterValue("@progArea", progArea);
                CrystalRepSource.ReportDocument.SetParameterValue("@attendanceEndDate", LastDayOfMonth(SessionHandler.WBL_EndDate).ToString());
                break;
The case statement actually has about 20 reports in it it is basically used to send the appropriate parameter set to the report and setup the database logon info, the if statement around the case checks if the load is a postback (to allow paging of the report) if it is it won't run the code or if a parameter has changed if one has it will rerun the code. As I said this worked in CR basic.
Unfortunately what now seems to happen is the first time I run a report it works fine, if I then leave the page and run a report requiring different parameters it will give me the parameter error. However if instead I run a report requiring the same parameters it will show the original report document as if it is coming from cache I think. The case becomes a bit more bizarre later as I have created the ability to change a parameter without leaving the report page this actually does a postback and changes the report to the proper one with the proper data.
So it seems to me the code to change report is working first time and for postback but not for re-entering the page. I am really stuck been working on this for hours  any ideas.

Answer 1

ok i have found the solution after a quite a while so anyone else getting this I was using the line:
CrystalRepSource.Report.FileName = SessionHandler.RunReport;
I changed it to:
CrystalRepSource.ReportDocument.Load(Server.MapPath(ReportName));
This clears any existing report and loads the correct one seems to have solved all my problems.