Maybe if your tamagotchi is on the third generation then you might accidently be typing in the grand parent code or it could be that you are not typing in the parent code quick enough because it changes every few seconds. The make-up costs 80p from the shop only on version three tamagotchis and to use it your tamagotchi has to be an adult. When you use the make-up, your tamagotchi will put in on and then it will either show itself with make-up on or it will refuse to. If you buy a mirror in the shop for 3000p, hten your tamagotchi will put the mak-up on infront of the mirror. The mirror is re-useable but the make-up isen't. I hope that I helped!