Mysqli outputting 10 random rows

I would like to retrieve 10 random rows from my database, each time i refresh the page i want the random rows to change.

I have made a query and a while loop to output all 10 results however i am just getting a blank page in return, there is no errors, nothing....

Its probably something silly i have missed out, but i just cant find it.

Here is my PHP :

<?php
include '../dbconnect.php';


$res = $conn->query("SELECT id FROM messages ORDER BY RAND() LIMIT 10");
while($row=$res->fetch_array())
{

 echo $row['id'] . "<br>";

}


?>

Thankyou for any help