Stampare dei valori XML in PHP

[Kitt3000]

Salve, sto cercando di far stampare un file PHP dove stampi solo due valori di due tag in xml, title e artists. Ecco il file XML:

<tracks>       
<radioname>Ixtreme Radio</radioname>        
<rank>0</rank>        
<isradionomy>1</isradionomy>        
<radurl>http://www.radionomy.com/ixtremeradio</radurl>        
<track>            
<uniqueid>4014324288</uniqueid>            
<title>Mask Off</title>           
 <artists>Future</artists>            
<starttime>2017-06-28 23:25:02.303</starttime>            
<playduration>201803</playduration>            <current>1</current>                                <cover>http://i3.radionomy.com/tracks/232/04aebbff-c2d9-4d47-a570-44b5f55edd3d?radiouid=80b5e81c-c769-478a-aee7-fbe149aacfe3</cover>                                                             <callmeback>68525</callmeback>                                                                        </track>                     </tracks> 

Ho provato a fare così:

<?php
$xml=simplexml_load_file("http://api.radionomy.com/currentsong.cfm?radiouid=80b5e81c-c769-478a-aee7-fbe149aacfe3&apikey=cf415862-c0ac-4085-bc03-be80a26f9063&callmeback=yes&type=xml&cover=yes&previous=yes.xml");

echo "Canzone in onda: $xml->title di $xml->artists";?>

ma non funziona.. come posso fare?
grazie