Im playing as a Assassin and i got the Critical Charge perk (Can do a one-handed power attack while sprinting that does double critical damage ) from one-hand skill and tried to combo with the Silent Roll perk (Sprinting while sneaking executes a silent forward roll ) so that i could do a critical damage atack (critical charge) and a sneak atack at the same time.
But the damage doesnt seems to scale here,.

How critical strikes, critical damages really works??

As far as I know, I don't think Critical Charge works when your in sneak as you are doing action rolls, not "sprinting" in one successive motion.

You are actually doing this: Action Roll -> Stop -> Power Attack -> Sneak Attack bonus only.

Also that's probably why Critical Charge is in the One-Handed skill, it was meant for "charging attacks", otherwise it would have been under the Sneak skill and would have worked.

anyone?

It works... i receive both messages : Sneak atack 6x time and critical damage.
Actualy there is no reason to not work. What im doing is sprint while sneak( Silent roll makes it possible for a short time) and do a power atack,

But forget about this.... how much critical damage does? IS it a multiplier of weapon damage? How much?

I have a feeling you must be standing and sprinting to get that bonus.

As i said i already got that bonus. I just dont know how much is this bonus. How much bonus damage critical atack does?

Sorry I am not sure. You may have to test it yourself.

I can tell you that power attacks do about 2x more damage than your normal attack. I tested this myself on a giant. My normal sneak attack takes away half of a giant's health. A sneak power attack kills the giant completely.