Certain command on Minecraft realms are not working

So basically, I bought a Minecraft realm and I've noticed that some commands don't work such as /kick, /ban, and quite a few others that at this point I cannot remember..
When I try these commands it says "You do not have permission to use this command". This confuses me more so, as I am the admin/ buyer of the Realm.

I'd really appreciate help or replies on whether this is normal or perhaps a mistake?
Thanks c: