i cant spawn certain mobs on creative mode and havent seen them on survival either

the version is actually mcpe 0.9.0 build 12, but it wouldnt let me choose mcpe. in infinite world size, i cant spawn zombies, zombie pigmen, slimes, skeletons, silverfish, endermen, spiders, or creepers. i could not spawn them in creative, and i couldnt find them in survival mode.