Speaker and Cmd bug

[crush4win]

I don't know why I get this error when I type a command with a space at the beginning in my minecraft server console. Actually, it's not the only command (For example: normal command /kit I get this error when I type / kit in the server console), I also get a speaker from the game with /oa speaker , but I get a player head in my hand, and when I put it on the ground, I can't right click on it, so it doesn't open.

[crush4win]

I solved the problem once I opened my inventory after getting the speaker with the command. I think I need to open the inventory otherwise it can't be fully loaded