ReportViewer.dwp not working

I'm getting this error while try to open ReportViewer.dwp

Message : Name=Request (GET:http://xxxxxxxx/_layouts/WPPrevw.aspx?ID=64)
Message : Site=/
Message : Leaving Monitored Scope (EnsureListItemsData). Execution Time=8.7358
Message : Microsoft.Reporting.WebForms.SessionDisabledException: Session state 
      has been disabled for ASP.NET.  The Report Viewer control requires th
      at session state be enabled in local mode.    at Microsoft.Reporting.
      WebForms.ReportViewer.EnsureSessionOrConfig()     at Microsoft.Report
      ing.WebForms.SessionKeepAliveOperation.CreateRequest(ReportViewer vie
      wer)     at Microsoft.Reporting.WebForms.ReportViewerClientScript.Set
      ViewerInfo(ReportViewer viewer, String reportAreaId, String promptAre
      aRowId, String docMapAreaId, String fixedTableId, String promptSplitt
      erId, String docMapSplitterId, String docMapHeaderOverflowId, String 
      directionCacheId, String browserModeCacheId)     at Microsoft.Reporti
      ng.WebForms.ReportViewer.OnPreRender(EventArgs e)     at System.Web.U
      I.Control.PreRenderRecursiveInternal()     at System.Web.UI.Control.P
      reRenderRecursiveInternal()     at System.Web.UI.Control.PreRenderRec
      ursiveInternal()     at System.Web.UI.Control.PreRenderRecursiveInter
      nal()     at System.Web.UI.Control.PreRenderRecursiveInternal()     a
      t System.Web.UI.Control.PreRenderRecursiveInternal()     at System.We
      b.UI.Control.PreRenderRecursiveInternal()     at System.Web.UI.Contro
      l.PreRenderRecursiveInternal()     at System.Web.UI.Control.PreRender
      RecursiveInternal()     at System.Web.UI.Control.PreRenderRecursiveIn
      ternal()     at System.Web.UI.Control.PreRenderRecursiveInternal()   
        at System.Web.UI.Control.PreRenderRecursiveInternal()     at System
      .Web.UI.Control.PreRenderRecursiveInternal()     at System.Web.UI.Con
      trol.PreRenderRecursiveInternal()     at System.Web.UI.Control.PreRen
      derRecursiveInternal()     at System.Web.UI.Control.PreRenderRecursiv
      eInternal()     at System.Web.UI.Control.PreRenderRecursiveInternal()
           at System.Web.UI.Control.PreRenderRecursiveInternal()     at Sys
      tem.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPo
      int, Boolean includeStagesAfterAsyncPoint)     at System.Web.UI.Page.
      ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean include
      StagesAfterAsyncPoint)     at System.Web.UI.Page.ProcessRequest()    
       at System.Web.UI.Page.ProcessRequest(HttpContext context)     at ASP
      ._layouts_wpprevw_aspx.ProcessRequest(HttpContext context)     at Sys
      tem.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpAppli
      cation.IExecutionStep.Execute()     at System.Web.HttpApplication.Exe
      cuteStep(IExecutionStep step, Boolean& completedSynchronously)
   Message : Leaving Monitored Scope (Request (GET:http://xxxxx/_layouts
      /WPPrevw.aspx?ID=64)). Execution Time=70.1226