The description of Dispel Magic says:
Choose an object, creature, or magic effect within range. All to spell level 3 or lower on the target's purpose.
And Animate Dead has a duration of:
So there is no spell effect to dispel, since Animate Dead has an instant duration, so Dissipation of Magic only works on a spell on which it has nothing to do and does nothing. Also clearly stated in this Sage notice:
Can you use dispel the magic on the creations of a spell like animate the dead or affect these creations with antimagic field? Whenever you wonder if the effects of a spell can be dispelled or suspended, you must answer a question: Is the duration of the spell instantaneous? If the answer is yes, there is nothing to dispel or suspend.
The undead control granted by the spell is a consequence of the spell used, not a permanent magical effect, in the sense that fires triggered by a fireball are a permanent non-magic effect. The zombies are strictly faithful to the caster for a while, tied to them like ducklings to their mother, and in the same way, fires and damage caused by a fireball last for a while and can not be dissipated. link.