Unavailable to use my Nickname In-Game.

[LadyKaos]

I would like to know why i cannot use LadyKaos as nickname in-game it said that It's unavailable but I searched in the armory and nobody has that nickname.

I use this one since TBC. WOTLK here, so on MOP I haven't do it yet cuz it doesn't let me.

[Zardonic]

Armory displays only characters above level 10.
And someone has [reserved] 'ur' name, if it's unavailable.

[LadyKaos]

Armory displays only characters above level 10.
And someone has [reserved] 'ur' name, if it's unavailable.

Ohh! Ok I understand now anyway ty for your quick answer.

[Anyone0]

It's most likely not taken. But you can not use it. There is a specific rule in Blizzards naming policy:

Minor violations include any names that:
Consist of any title prefix attached to a character's name, fantasy-based or not (e.g. Kingmike, Presidentsanchez).

WoW client has a list of forbidden names in it. Because of that rule it won't let you use any name starting with "Lady". Just tested it on wotlk and it should be same on MoP.