Quote Originally Posted by Man_Over_Game View Post
Dispel doesn't have to target the effects of a spell; it works fine on generic magical abilities too as long as they're identified as "magical".

The question is whether the illusion is technically considered magical or not. I can't read up on it to determine if it's explicitly labeled as "magical", and it wouldn't make sense if it wasn't, but that's a possibility.
There are illusions and other magical effects that simply can’t be dispelled.