"Actions not set to action bars cannot be used" bug

Whenever I try to execute any action via the text command, e.g.

/ac "Fists of wind" <me>

I get the "Actions not set to action bars cannot be used." message even though the action IS equipped. So far it doesn't seem to matter which action I am trying to execute. I only started using this recently, so I can't say since when this started happening, but I heard others saying they have to re-set the action to get it to work again. I can't do this because in case of the Fists, you can't remove it from the bar.

ISP: 1&1
Type of Internet Connection: ADSL
Internet Connection Speed: 3500kbps
Date & Time: N/A
Frequency: always
Character Name: Crim Soukyuu
Race: Dunesfolk
World: Trabia
Class/Level: MNK/50
Area and Coordinates:N/A
In-Game Time: N/A

Commands are case-sensitive. If what you have posted is exactly what you're using in-game, it doesn't work simply because the command is invalid. While I would like to see them remove the case-sensitive nature of commands, it's not really a bug, per se.

/ja "Fists of Wind" <me>

The above command should work for you. The W in Wind must be captialized.

Hello Soukyuu,

Thank you for posting your concern over your abilities not activating using the commands. In this case can you please try what Raldo has suggested? (e.g. using the case sensitive terms /ja "Fists of Wind" <me> in place of the command that you listed). And if that works for you, excellent! Though if that does not work please let us know here so we can submit this for you at that time. Thanks again and have an excellent day!

It was the case-sensitivity indeed. The error message, however, is pretty misleading.
Usually, when the syntax is wrong, the command is simply displayed as is without being executed, so I thought it might be a bug...

Hello Soukyuu,

I understand your concerns about the error message, but am glad that the issue has been resolved. We are glad that you brought this to our attention, and appreciate you doing so whenever you believe you encounter what seems to be a bug. Thank you again for the post, and good hunting!