I'm creating a trainer with C# i need some help

Make sure you have the right file.

http://static.miniclipcdn.com/games/8-ball-pool-multiplayer/en/game_v3.3.2DAyyyyy.swf

I found the class PoolCanvas (§-_-__-----____§.PoolCanvas) in that file with ffdec.

It's possible that the method of hacking through PoolCanvas is patched
Another possibility is that you're entering the AOB too late so the original is already loaded in memory and never updated afterwards.

Why not just write a LUA script and use it with Cheat Engine? Isn't that simpler as you can feed AOB data.