new error
CS0433: The type 'Microsoft.Reporting.WebForms.ReportViewer' exists in both 'c:\Windows\assembly\GAC_MSIL\Microsoft.ReportViewer.WebForms\10.0.0.0__b03f5f7f11d50a3a\Microsoft.ReportViewer.WebForms.dll' and 'c:\Windows\assembly\GAC_MSIL\Microsoft.ReportViewer.WebForms\9.0.0.0__b03f5f7f11d50a3a\Microsoft.ReportViewer.WebForms.dll'
i just update VS from 2008 tp 2010 and user rdlc report