Thanks Phil. I have actually read the spell.
I wasn't trying to be condescending; it was just convenient for me to copy and paste the spell description in order to cite my interpretation of the rule.
Zombies automatically being under control of the caster is certainly implied by "adds one zombie to his warband" . The Control Undead spell had me wondering if it was explicitly stated somewhere.
It seems to me that Control Undead is a limited use spell that can be used to (A) control another necromancer's zombie, or (B) control a randomly generated undead creature (assuming random creatures are implemented). It's too bad that the necromancer can't at least summon a few more undead creatures.
Regarding the Summon Demon spell, it is a bit different in that it states, "The demon is treated as though it is already subject to a Bind Demon spell." I think the difference in wording as compared to the Raise Zombie spell is that a demon cannot be summoned between games and is therefore not "added to the warband" as such.