eevee doesn't evolvle into umbreun you need to make it happines full in the night

You do have to level up your eevee at night to make it evolve into an umbreon. I used an
EXP share on my eevee to help it level up quicker. And it evolved at level 29. but it may
be different for your eevee.

also if you want an espeon, level up your eevee durring the day. and once its happiness
(or friendlyness towards you) gets high enough, it will evolve.

if you want to make sure to get a certian one, you can change the time in your ds settings
to keep it at night for umbreon, or at day for espeon.

i have done this myself and i now have 3umbreon's and 3espeon's.

This WILL work :)

u have to give it lots of protiens and/or rare candys and then it will be happy. then
level it up and it will evolve