Update UPDATE PHP

Good evening, I'm trying to update a kettle delivery record, I click the button to update and update it right in the bank, but when I update the same order again, the information is not updated, only after a time of first UPDATE that the data is updated in the bank ... example if I updated status to in transit now, only after a few minutes to update the status to delivered. Does anyone know how to help me?

if($pedido > 0 && $status > 0){

 $atualizar = mysql_query("UPDATE pedidos SET id_status = '$status' WHERE 
 id_pedido= '$pedido'");

        if($atualizar){
            echo "atualizado, pedido $pedido e status $status";
        }else{
            echo "erro ".mysql_error();
        }
}

HTML:

<tr>
 <td>
  <?php echo $linha["id_pedido"]; ?>
 </td>
 <td>
  <select name="status">    
   <option value='2'> Em Trânsito </option>
   <option value='4'> Entregue </option>
 </select>
 </td>
 </tr>