Why can't I enchant past 10% magicka regen?

[Dan Fielding]

I have my perks at "enchanting is 80% stronger" and "skill enchantments are 25% stronger", while using a grand soul gem filled with a grand soul. And yet my Enchantment "Fortify Restoration & Magicka Regeneration" maxes out at Restoration spell cost 12% less and Magicka regenerates 10% faster. In fact the 10% magicka regeneration doesn't change no matter what I do. Is this a glitch? I've found cloth armors with 17% and 75% respectively, I;m trying to enchant my plate armor.

[Grathagis]

10% is the maximum because it is fixed to another enchantment.

[Dan Fielding]

What does "fixed to another enchantment" mean?

[The Graper]

When you disenchant mage robes, it gives/gave you a 10% bonus. That percentage is now set and stone and cannot be raised, even if you have a higher level in enchanting.
Don't take my word for it, thats just how I remember it.

[Grathagis]

The enchantment in question is combined of 2 parts: the skill and the regeneration.
The first one is variable and depends on your enchanting skill. The second one is fixed.
There is however a magicka regeneration version that stands alone, and that one can be improved by the enchantment skill.

[Bullwinkle]

Maybe try a potion of Fortify Enchantment? If you have not used one before, it wears off very quickly, so do a dry run to practice before you do it for real. Also wouldn't hurt to make sure you have no strange curses or diseases in your Active Effects.