You must log out of the game to create sales (problem)

I have a character on Frostwolf server which i m trying to sell for 30 coins. However this message always pops up when i try to sell. Im logged out ofcourse and ive waited like 10 minutes but nothing changes. The same message keep coming nd coming!

character name : Eyolf
Server : Frostwolf

Restart your pc and try again

Ive done it like 3 times. Ive even closed it completely qnd tried from the cellphone...There seems to be something wrong and the only message to appear is this....

It works for me everytime.
Sorry i couldn't help you.