If you drag and drop a soap function from the navigator pane the PHP code is not right, it is actually SoapClient not
SOAPClient.

Also if you are using php 5.3 or greater then is it best to use \SoapClient rather than SoapClient in case the user is
in a namespace, the same for Exception.  The correct code would be something like this.  If you can detect a namespace
declaration in the file then it would be even better.

Sorry if this is a bit pedantic :)

try {
    $wsdl_url = 'url';
    $client     = new \SoapClient($wsdl_url);
    $params = array( 
    );
    $return = $client->login($params);
    print_r($return);
} 
catch(\Exception $e) {
    echo "Exception occured: ".$e;
}