Did you reload the game and retry the action?
I was unable to reproduce the problem, I have tried and I could execute the action you describe without issues. The error message you have reported sometime happens when there are temporary glitches on the server.
If it is reproducible for you let me know and I'll look deeper.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum