Getting proble to display data in crystal report

CrystalReport2 obj = new CrystalReport2();
                SqlConnection con = new SqlConnection();
             //This is connection class that return string.
                ConnectionClass cc = new ConnectionClass();
                con.ConnectionString = cc.GetConnection();
                con.Open();
                //ds = new DataSet();
                DataSet2 ds = new DataSet2();
                SqlDataAdapter da = new SqlDataAdapter("Select * from Sample", con);
                SqlCommandBuilder builder = new SqlCommandBuilder(da);
                da.Fill(ds, "Sample");
                obj.SetDataSource(ds);
                crystalReportViewer1.ReportSource = obj;