"Missing parameter values." -- Export and Print only...

Question

I have a web application and I am using CrystalReportViewer.  I am passing several parameters to Crystal using: 
report.SetParameterValue(field.Name, Session[field.Name]);
I have session variables which will hold parameters needed to pass into the report.  The session variables are populated from controls on my webpage after an onclick event.  This even not only populates session, but also passes parameters to the report with the following code: 
ReportDocument report = new ReportDocument();
Session["MapPathName"] = "./Reporting/CaseStudy.rpt";
report.FileName = Server.MapPath(Session["MapPathName"].ToString());
ParameterFields fields = new CrystalDecisions.Shared.ParameterFields();
fields = report.ParameterFields;
foreach (ParameterField field in fields)
      report.SetParameterValue(field.Name, Session[field.Name]);
CrystalReportViewer1.ReportSource = report;
This works great for reporting and is very extensible.  However, when clicking on the "Print" or "Export" buttons on the toolbar I get "Missing parameter values."  I attempted to export manually in code using the .ExportToStream function but I still get the error, "Missing parameter values." 
I received this error also in Refresh, Search, and Navigate functions.  This was corrected by calling a function that supplies the above code block to these functions.  However, I do not see any events for controlling the Print nor the Export events. 
QUESTION: How can I print or export a report when passing parameters using CrystalReportViewer?  Thanks in advance!
P.S. - Crystal Reports XI Release 2
Edited by: KyleSavant on Jun 18, 2009 5:42 PM

Answer 1

There are no Export or Print events accessible for the viewer
Since it sounds like you are creating the reportdocument object in your click event, the settings on this object become out of scope on successive postbacks executed by other events.
to get around this without major changes, you can place your "report" object in session in this event and retrieve it from session on successive postbacks.  This should solve your problems around navigation, printing and exporting.  What you will need to do is check if the session object exists (usually in page_load or page_initialze) and if so, retrieve it from session and bind it to the viewer's reportsource.  If the session object does not exist, then do nothing (ie you have not clicked your button yet that retrieves the parameter values from session and loads the report).  Also, in your click event you can check if the report session object exists and if so, remove it so that it can be re-created with your new parameter values (ie i'm assuming the only time you want to set parameter values is in this event).
Dan