Error during processing of the ConnectString expression of data source

Thanks for Carter33 who post at http://social.msdn.microsoft.com/Forums/sqlserver/en-US/447b14c0-f1d0-4980-a2cd-8f2069804801/receiving-a-datasource-error-when-running-report-that-uses-expression-based-connection-string?forum=sqlreportingservices , manually move the report parameters section of the rdl file on the top of datasource section fixes the issue.