According to this source http://www.uesp.net/wiki/Skyrim:Smithing and many others, with smithing skill at 100 level and all the perks I should be able to improve my armor by 20 points, but what I discovered is that it's not correct for me. For examlpe Deadric Boots with 26 armor(btw according to wiki, it should be 18, I don't have any perks in Heavy Armor) the improvement is to 42, so it's  16 points. I don't have any clothes, gear or active magical effect on me. Turned off all the mods and it's still the same. What should I do?