xml validation code is wrong

[staabm]

the code sample - provided by me in fa985ed - doesnt work :/.

I tried a lot of different ways but wasnt able to find one which works using the xml-extension.
As a workaround I localy work with a DOMDocument based approach:

    static private function validateXml($xmlString, $schema) {

        $libxml_display_error = function ($error)
        {
            $return = "";
            switch ($error->level) {
                case LIBXML_ERR_WARNING:
                    $return .= "Warning $error->code: ";
                    break;
                case LIBXML_ERR_ERROR:
                    $return .= "Error $error->code: ";
                    break;
                case LIBXML_ERR_FATAL:
                    $return .= "Fatal Error $error->code: ";
                    break;
            }
            $return .= trim($error->message);
            if ($error->file) {
                $return .=    " in $error->file";
            }
            $return .= " on line $error->line";

            return $return;
        };

        libxml_use_internal_errors(TRUE);

        $xml = new \DOMDocument();
        $xml->loadXml($xmlString);

        if (!$xml->schemaValidate($schema)) {
            echo '> DOMDocument::schemaValidate() Generated Errors!'."\n";
            echo 'Schema:'. $schema;

            var_dump($xmlString);

            $errors = libxml_get_errors();
            foreach ($errors as $error) {
                debug($libxml_display_error($error));
            }
            exit();
        }
    }

just to let you know...