Cannot finish enchantment
I want to enchant my elven gilded armor (flawless) with increased carrying capacity with a filled black soul gem, but it won't let me finish it.
You are trying a combination that is not possible. According to this table you cannot apply a Carry Weight enchantment on chest armor. You can apply it to boots, gauntlets/gloves, rings and necklaces. Either try a different piece of equipment or a different enchantment.
After selecting the armor, compatible enchantments should be highlighted.