Game Mechanics: Stonestance monk bug?

[fonain]

I have been having issues the last 2-3 days with my new Stonestance discipline. It is supposed to dampen all melee damage by xx% for 12 seconds. It worked without a problem for most of the time, but lately it becomes unactivated almost immediately after i activate it. After the first successful melee hit against me, or my first movement, it deactivates.