Holy Spark

http://www.wowhead.com/spell=33333/holy-spark

Hello, I'd like to know if there's anyone with same problem. I know that Holy Spark (2p pvp holy/disc set bonus) is bugged but I've asked nearly 10 priests and everyone has told me something different. For 1 priests it works well all the time, for other priest Holy spark appears from time to time and for others Holy Spark works, but it disappears when they use any AOE heal. In my case though, Holy spark doesn't even appears, ever. So my question is, "is there anyone who has the same problem as I do?" And I mean my problem, problem when your Holy spark never appears. Or is there anyone who knows why my Spark works for 0% and it works (with bugs though) for the others. That spell is crucial for Holy rotation and I'd be glad if it worked for 50% at least.
Thank you

PS: ofc I wrote bugreport but it has been blocked as duplicat bcs there was other report of Holy Spark, ofc it was different bug, just developer hasn's read my report, just looked at title and... woala duplicate.