Some Warden/Warrior skills have been broken and no longer activate when you use them. The "fix" that was supposed to happen 3 weeks ago has yet to been seen.
If not, it could also be bad ping. Recently, I, and looking one forums, many others, have been experiencing bad ping spikes . At about 300 ping, you get a delay, and skills you click on activate a few seconds after you click on them. Sometimes my ping spikes to a couple thousand, and my skills just fail to activate all together until ping drops down to normal.