New user web service

This is a bit frustrating,

I am trying to add new user using a web service , these are my parameters:

    $user1 = new stdClass();
    $user1->username = "testing";//trim(urlencode(filter_var($_POST['arr']['user_email'],FILTER_SANITIZE_STRING)));
    $user1->password = "asdL1232";//trim(filter_var($_POST['arr']['user_password'],FILTER_SANITIZE_STRING));
    $user1->firstname = "testname";//isset($name[0]) ? urlencode($name[0]) : '';
    $user1->lastname = "testlastname";//isset($name[1]) ? urlencode($name[1]) : '';
    $user1->email = "tests@gmail.com";//urlencode(filter_var($_POST['arr']['user_email'],FILTER_SANITIZE_STRING));
    $user1->auth = 'manual';
    $user1->surname = 'asdsad';
    $user1->country = 'Israel';
    $user1->lang = 'he';
    $user1->idnumber = '';
    $user1->theme = 'standard';

and this is the server response:

"Invalid parameter value detected | ERRORCODE: invalidparameter"

I cannot understand which parameter is wrong...

can anyone help ?

Thanks