Player List Problem

So I try to get a player list. It works on some servers and not on some
[Player list works](https://mc-api.glitch.me/api.php?host=play.nethergames.org&port=19132 )
[no player list](https://mc-api.glitch.me/api.php?host=rupture.pro&port=25565) 
Is this a problem with minecraft or with the code?