Knagart

hi there, i ve enchanted my skill enchanted in M.Power to +20 but the skill effect is not 20% but 8.1% for all skills attack its the same for the other skills for exemple Body to Mind enchanted on power to+15 give a skill power +15% i did those enchant long ago, is it normal that my attack skill enchanted to +20 have only +8.1% skill power?? thx for your answers and advice PS : i obviously send a ticket but the gm..... i let you fisnih the sentence....