Why my data cannot display out at php ?

        <?php

        require_once './includes/config.php';


        $con = new mysqli(DB_HOST,DB_USER,DB_PASSWORD,DB_NAME);


        $sql = "SELECT * FROM contact-info";


        if($result = $con->query($sql)){

            while($row = $result->fetch_object()){
                //display record 1 by 1  
                printf(' 
                        <tr> 
                        <td>%s</td> 
                        <td>%s</td> 
                        <td>%s</td> 
                        <td>%s</td> 
                        <td>%s</td>
                        </tr>
                           ',$row->id,
                             $row->name,
                             $row->email,
                             $row->phone,
                             $row->comment);
            }

        }

        printf('
                <tr> 
                <td colspan="5">
                %d record(s) returned. 
                [ <a href="insert-student.php">Insert Student</a> ]
                </td>
                </tr>
                ',$result->num_rows);

        $con->close();

        ?>