Reuse Crystal report Viewer For different reports - unload cache

Question

So I am migrating from crystal reports basic to crystal reports 2008. I have hit a stumbling block. Rather than have a new page and report viewer for each report I decided it would be easier to have one report viewer and send to it in session variables the report I wish to run and appropriate parameters. This seemed to work fine in CR basic.
Now I have upgraded the viewer works fine for the first report I run however it then caches this report and doesn't seem to clear it down, if the new report has different parameters I will get a parameter error. If I run a report requiring the same parameters I will get the original report not an updated one.
I believe I need to leave the CrystalReportSource cache on in order to page the report (correct me if I am wrong)
I have taken a few snippets of code, is this possibly running too late in page life cycle have I missed something or is there a way to force a cache clear:
protected override void OnLoad(EventArgs e) {
//setup report in viewer with correct db logon
                CrystalRepSource.Report.FileName = report;
                SetupLogonInfo(CrystalRepSource);
                //add parameters
                AddParam(paramFields, pfItem1, dcItem1, "@year", year);
                AddParam(paramFields, pfItem2, dcItem2, "@school", school);
                AddParam(paramFields, pfItem3, dcItem3, "@division", division);
                AddParam(paramFields, pfItem4, dcItem4, "@progArea", progArea);
                AddParam(paramFields, pfItem5, dcItem5, "@type", SessionHandler.record_type);
                AddParam(paramFields, pfItem6, dcItem6, "@filterText", "School = \'" + school +
                                                        "\' Division = \'" + division
                                                        + "\' Programme Area = \'" + progArea
                                                        + "\' Record Type = \'" + SessionHandler.record_type_text + "\'");
CrystalViewer.ParameterFieldInfo = paramFields;
private void SetupLogonInfo(CrystalReportSource CrystalRepSource)
        TableLogOnInfo logOnInfo = new TableLogOnInfo();
        logOnInfo = CrystalRepSource.ReportDocument.Database.Tables[0].LogOnInfo;
        ConnectionInfo connectionInfo = new ConnectionInfo();
        connectionInfo = logOnInfo.ConnectionInfo;
        connectionInfo.DatabaseName = Application["db"].ToString();
        connectionInfo.ServerName = Application["server"].ToString();
        connectionInfo.Password = Application["pass"].ToString();
        connectionInfo.UserID = Application["user"].ToString();
        CrystalRepSource.ReportDocument.Database.Tables[0].ApplyLogOnInfo(logOnInfo);
    private void AddParam(ParameterFields paramFields, ParameterField pfItem, ParameterDiscreteValue dcItem, string fieldName, string value)
        pfItem.ParameterFieldName = fieldName;
        dcItem.Value = value;
        pfItem.CurrentValues.Add(dcItem);
        paramFields.Add(pfItem);

Answer 1

ok so I have tried changing the code to:
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 + "\'");
private void Page_Unload(object sender, EventArgs e)
        try
                CrystalRepSource.Report.DataSources.Clear();
                CrystalRepSource.Report.Parameters.Clear();
                //CrystalRepSource.ReportDocument.Close();
                //CrystalRepSource.ReportDocument.Dispose();
                CrystalRepSource.Dispose();
                CrystalViewer.Dispose();
                GC.Collect();
        catch { }
I experimented with various bits in the page unload as you can see I have commented a bit out at present as it was throwing an exception. The SetParametersValue while handy (will clean the code up a bit) didn't make any difference I am still getting the same issue.