Problem with embedding CrystalViewerControl inside a Custom Web Control

Question

I'm building a Custom Web Control in ASP.NET 2.0 that embeds the CrystalViewerControl inside it. The CrystalViewerControl accepts its ReportSource as a ServerFileReport, that means that my report file I'm trying to view is accessed as a Web service. I successfully render and create the CrystalReportViewer control and the ServerFileReport object, but I can bind them. Eg:

 
 CrystalReportViewer viewer= new CrystalReportViewer;
 ServerFileReport server= new ServerFileReport();

 server.ReportPath=@"\report.rpt";
 server.WebServiceUrl="http:\\localhost\report_service.asmx";

 viewer.ReportSource=server;

The problem is after I assign the ServerFileReport object to the ReportSource property the property remains null, the assignment doesn't work. This behavior happens only inside my Custom Web Control.