Oh my, where to start.
The amount of talentpoints you spend in the two trees is quite common, however the choices you picked are waaay off. You are missing two MUST HAVE talents and the talent that increases your dps the most in a raid.
You NEED to get Ruin. In every single build you can make as a warlock that has PvE in mind. ALWAYS.
Secondly you don't pick Nightfall. A free SB now and then is a pretty neat thing to get when you try to crank up your dps. Also helps you keep up SE stack when you get below 25%. Which conveniently is my next point.
Once below 25%, drop Immolate off your rotation and use DS as a filler, which means you need to get Soul Siphon as well.
An armory link and a WWS report will help you more than anything when you ask for advice on how to improve. Getting these talents is a start.
I'd recommend this specc for you instead:
http://www.wowhead.com/?talent=IfxMbzMAoVq0IstZyzhV
Keep your dots up all the time, start using Drain Soul as soon as you got your dots rolling when the target hits 25%.
That should help you a bit up the ladder at least. With your gear you should be doing quite a bit more dmg.
And finally, I hope you noticed that CoE and CoS got merged into one