Invalid Game Rules

When i write a game rule in the chat for example:

"/gamerule ExampleRule on"

The game does not recognize what i put .If i put

"/gamerule Hello World on"

the game gives me the message
"La regla de juego ha sido actualizada"
(The Gamerule has been updated, I play on Spanish 😃)

and not gives me the an error message or something like that.
I Don't know what's happening, is a 1.8 Vanilla, a normal world, i mean, it's a construction world, nothing with redstone or something like that, i attach some screenshots (In Spanish, sorry :c)
I Hope you maybe can fix that for the 1.9 or later!