An error has occured during report processing.Exception has been thrown by the target of an invocation.Object reference not set to an instance of an object

<pre lang="cs">public void ShowQueryBranchTATCrossed()
      {
          bool vFlag = false;

          try
          {
              rptViewer.Visible = true;
              //rptViewer.LocalReport.ReportPath="C:/Priya Working Folder/WorkingEnvironment/ILeverage2k10/ILeverage2k10/ILev_QueryBranchTATCrossedReport.rdlc";
              rptViewer.LocalReport.Refresh();

              vFlag = true;

          }
          catch (Exception Exp)
          {
              LogEvent(Exp);
              vFlag = false;
          }


          if (!vFlag)
          {
              ScriptManager.RegisterClientScriptBlock(this, typeof(string), "message", "alert('Unable to retrive the data, please contact system admin.');location.href='ILeverage_Blank.aspx'", true);
          }
      }