Did you try re-installing your game?
Maybe something is broken.....
This error often happens if someone does cancel skill animations. The skills still hit and do damage, you just cancel their animations. So that you can continue spamming the next skill faster after each other.
(At least that is what I got told by others, I do not PVP and do not cancel animations myself)
Could this be the case for you too?
If so try not to cancel the animation of that skill.
However, re-installling is still an option. If something really is broken that should fix it.
Edited by Fliederduft78, 21 February 2016 - 09:13 AM.