Are you *sure* you have fulfilled the skill requirements?
You need to get multiple levels of skills, not just one skill. For example,
Brutel Attack - Level 2
Requires Level 5 Critical Strike
So, you need to invest 5 skill points in "Critical Strike" to get the upgrade to the power. Level 3 of Brutal Attack, requires 8 skill points in Critical Strike.
It tells you in red what you need to get for each power if you select it in the specialities tab. Furthermore, if you have got the skill requirements, then it doesn't actually say "Brutal Attack 3" in the power selection tab. It just says "Brutal Attack" but if you read the description, it should say it is at Level 3.
Other than that, all i can say is, i don't think you have gotten the requirements to the powers. What level is your character, and what skills do you have? That would be more helpful. Also, if in doubt, check the "Dungeon Siege 2" section of this site, and look under "Powers" and it will tell you the requirements to all the powers.
Hope that helps, but i have never had this problem before, so all i can think of, is, you haven't fulfilled the power requirements. Let me know if i am wrong by posting your skills for me to look at. And check the powers, just to make sure they haven't actually increased in power. It doesn't change the name of the power (ie, Brutal Attack will always say "Brutal Attack" even if it is at level 1, 2 or 3. It won't say "Brutal Attack lvl 2" or "Brutal Attack Advanced" or whatever. So, make sure they haven't already gone up a level).
- Check the Powers Tab - look at the Requirements
- if no requirements, then look to see the level the skill is at
- if skills are highlighted in red, and begin flashing on the skill tree when power is highlighted, then the power can be upgraded by putting more skill points in the relevent skills
- post your current skills / powers, so we can see what is wrong
Check Here for Power Requirements: