After further investigation I found that the the problem was with the service used to get the users ip so I change the code as follows:
$url = 'https://www.geoplugin.net/xml.gp?ip='.$ip;
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$cdata = curl_exec($ch);
curl_close($ch);
$carr = simplexml_load_string($cdata);
$return = $countries["{$carr->geoplugin_countryCode}"];
return $return;
Note: If you are using the plugin on a localhost machine the ip would be 127.0.0.1 therefore the service will return a 404 error. so you may want to add an if statement to set a default county code if the ip is 127.0.0.1.