if(isset($_POST['submitArticle']))
        {
            $artikel = $_POST['article'];
            $aantal = $_POST['quantity'];
            $a=0;

            $art = array();
            $quan = array();

            foreach($artikel as $key => $value)
            {
                $art[] = $artikel[$a];
                $quan[] = $aantal[$a];

                $a++;
            }
            $artikelArguments = array_combine($art, $quan);

$client->getArticle($artikelArguments);

public List<string> getArticle(List<KeyValuePair<int, int>> articles)
            {
               //Get articles based on ID
               foreach (KeyValuePair<int, int> art in articles)
               {

Fatal error: Uncaught SoapFault exception: [a:InternalServiceFault]