Looks like missing reference of the Reportviewer 10. Error tells exactly you need to do.
Add handlers in your Web.Config:
<add verb="*" path="Reserved.ReportViewerWebControl.axd" type = "Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
to the system.web/httpHandlers section of the web.config file.
Try!