function retrieveProfile()
{
$url = \"http://steamcommunity.com/profiles/{$this->steamID64}/?xml=1\";
$profileData = simplexml_load_string($url);
if
You are loading the URL as your XML source. You should have:
$profileData = simplexml_load_file($url);
Url was changing from steamcommunity.com/profiles/76561197991676121/?xml=1 to http://steamcommunity.com/id/virusbogdan/?xml=1 . Obviously the first link returns null so there was an error. Problem solved !