Command blocks wont /kick or /ban

I made a world and wanted to use /kick so i could kick a player with a message (Welcome to our server network) but it did not do anything - it showed NOTHING in the server log or to op's but mostly - it didn't kick me

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More details
I was OP
I was only player online
I was only op
I was powering it with a pressure plate
I was on a Vanilla server (Not LAN)
I had no MODs installed
I had an offline server (But not a LAN)

Not sure if any of these will help!
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