Web services

Hello All @David I am trying to use https://github.com/moodlehq/sample-ws-clients/tree/master/PHP-SOAP could you give me clue why the following error is displayed? Thank you Warning: SimpleXMLElement::xpath(): Undefined namespace prefix in /Applications/XAMPP/xamppfiles/htdocs/HRM/soap.php on line 54 Warning: SimpleXMLElement::xpath(): xmlXPathEval: evaluation failed in /Applications/XAMPP/xamppfiles/htdocs/HRM/soap.php on line 54 SoapFault Object ( [message:protected] => Invalid parameter value detected | ERRORCODE: invalidparameter [string:Exception:private] => [code:protected] => 0 [file:protected] => /Applications/XAMPP/xamppfiles/htdocs/HRM/soap.php [line:protected] => 69 [trace:Exception:private] => Array ( [0] => Array ( [file] => /Applications/XAMPP/xamppfiles/htdocs/HRM/soap.php [line] => 69 [function] => __soapCall [class] => SoapClient [type] => -> [args] => Array ( [0] => core_user_create_users [1] => Array ( [0] => Array ( [0] => stdClass Object ( [username] => testusername1 [password] => Testpassword1! [firstname] => testfirstname1 [lastname] => testlastname1 [email] => testemail1@moodle.com [auth] => manual [idnumber] => testidnumber1 [lang] => en [theme] => standard [timezone] => -12.5 [mailformat] => 0 [description] => Hello World! [city] => testcity1 [country] => au [preferences] => Array ( [0] => Array ( [type] => preference1 [value] => preferencevalue1 ) [1] => Array ( [type] => preference2 [value] => preferencevalue2 ) ) ) [1] => stdClass Object ( [username] => testusername2 [password] => Testpassword2! [firstname] => testfirstname2 [lastname] => testlastname2 [email] => testemail2@moodle.com [timezone] => Pacific/Port_Moresby ) ) ) ) ) ) [previous:Exception:private] => [faultstring] => Invalid parameter value detected | ERRORCODE: invalidparameter [faultcode] => Receiver [faultactor] => invalidparameter [detail] => Invalid theme: standard ) here is the token: $token = '21f9cc43fff73f06d408a447554ddb2c'; $domainname ='http://localhost/moodle'; $functionname ='core_user_create_users';