Name Space error in vs 2010?

Question

Name Space error 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using CrystalDecisions.CrystalReports.Engine;

using CrystalDecisions.Shared;

using System.Data;

using System.Data.SqlClient;

using System.Configuration;

for the highlighted  namespace i am getting below error

CrystalDecisions coold not found (Are you missing directives or reference assembly)