Changing to a different report at run-time, in Ado.Net

BH
Hi, i'm using Visual Studio 2010 (c#) with Crystal Reports. I've used the instructions (Crystal Reports Guide To ADO.NET) for connection. However, i can't seem to figure out how to change the report.  For example: I have CrystalReport1.rpt connected to crystalReportViewer1. Now i want the user to be able to connect CrystalReport2.rpt.

Simply changing:

crystalReportViewer1.ReportSource = crReportDocument1;

to

crystalReportViewer1.ReportSource = crReportDocument2;

does not seem to work.  Do i need to somehow refresh it?

Thanks so much for your help.

Aron.