ReportViewerWebPart not working properly with GetParameters

I am programmatically adding a ReportViewerWebPart to an application page in SharePoint 2010.  I can get the report to render properly by setting the report path but when I do a ReportViewerWebPart.GetParameters() the report does not render.  I get the tool bar but then its just white where the report should be.

Here is an example

ReportViewerWebPart wp = new ReportViewerWebPart();
this.ChromeType = wp.ChromeType = PartChromeType.None;
wp.ToolBarMode = ToolBarDisplayMode.Full;

wp.ReportPath = string.Format("{0}/reports/{1}", defaultZoneURL, _reportToViewRelativeURL);

ReportParameterInfoCollection reportInfo = wp.GetParameters();

this.Controls.Add(wp);

Matt Klepeis