how to delete a data using checkbox

http://www.daniweb.com – i have a problem deleting a data using checkbox please help me here's my code admin.php <form id="form1" name="form1" method="post" action="deleteApplication.php"><table border='1' cellspacing='0' width='612'> <tr> <th bgcolor='green'><font color='white'>#</font></th> <th bgcolor='green'><font color='white'>Room No.</font></th> <th bgcolor='green'><font color='white'>Cust. Code</font></th> <th bgcolor='green'><font color='white'>Check In</font></th> <th bgcolor='green'><font color='white'>Check Out</font></th> <th bgcolor='green'><font color='white'>No of Rooms</font></th> <th bgcolor='green'><font color='white'>Room Type</font></th> <th bgcolor='green'><font color='white'>Function</font></th> </tr>                                         <?php $i = 0; $number = 0; while($row = mysql_fetch_array($result)){ $number++; ?>          <?php $i++; if($i%2) { $bg_color = "#EEEEEE"; } else { $bg_color = "#E0E0E0"; } ?>           <tr bgcolor='". $bg_color ."'>   <td><center><Strong><font color='red'><input name="checkbox[]" type="checkbox" id="checkbox[]" value="<?php echo $rows['cno']; ?>">   </font></Strong>   </center></td>   <td><center><Strong><font color='red'><?php echo $row['roomno']; ?></font></Strong></center></td>   <td><center><Strong><font color='red'><?php echo $row['cno']; ?></font></Strong></center></td>   <td><center><Strong><?php echo $row['checkin']; ?></Strong></center></td>   <td><center><Strong><?php echo $row['checkout'];  ?></Strong></center></td>   <td><center><Strong><?php echo $row['noofrooms'];  ?></Strong></center></td>   <td><center><Strong><?php echo $row['roomtype'];  ?></Strong></center></td>   <td><div align="center"><a href='edit.php?code=<?php echo $row[cno]; ?>' class="style1"><img src="Admin/img/save-icon.gif" width="16" height="16" alt="View" title="View Information"/></a>       <a href='sendmail.php?emailadd=<?php echo $row[emailadd]; ?>' class="style1"><img src="Admin/img/edit-icon.gif" width="16" height="16" alt="Email" title="Email"/></a></div></td>   </tr>  <?php } ?>                                 </table>                                 <div class="select"><strong>Other Pages: </strong>                                         <select>                                                 <option>1</option>                                         </select>                           </div>                                                           <label>                                 <input name="delete" type="submit" id="delete" value="Delete">                           </label></form> deleteApplication.php <?php include 'dbconnect.php';    if(isset($_POST['delete']))         {  $checkbox = $_POST['checkbox']; //from name="checkbox[]" $countCheck = count($_POST['checkbox']);    for($i=0;$i<$countCheck;$i++)                 {                         $del_id  = $checkbox[$i];    $sql = "DELETE from rent where cno = $del_id";  $result = mysql_query($sql) or die (mysql_error());                   }                         if($result)                 {                                        header('Location: index.php');                         }                         else                         {  echo "Error: ".mysql_error();                         }         }  ?> nothings happen everytime i click delete. (General)