Update Zone.php

src/Qiniu/Zone.php

@@ -73,7 +73,7 @@ final class Zone
      **/
     public static function queryZone($ak, $bucket)
     {
-        return ningbo();
+        return self::ningbo();
         /*
         $zone = new Zone();
         $url = Config::UC_HOST . '/v2/query' . "?ak=$ak&bucket=$bucket";