Need help with "/skin" command

[Slave Master]

Hello,
I have a minecraft premium account, I changed my skin some time ago, it didn't changed so I used command "/skin <myname>", it changed after that, but now, I am stuck on 1 skin, and even if I use "/skin reset", "/skin default", even relog and change my skin after every time I use this command nothing happens. Need help.
IGN: __SlaveMaster__

 

[YoussofHD]

Try /changeskin:setskin

 

[Slave Master]

It says that I have no permission, and I need to contact an admin to fix it

 

[Slave Master]

Nees solution