I'd try adjusting it 15-30 min earlier (or later) - if you're catching her at the deepest part of her sleep cycle, she won't feed but if you can get her in a lighter stage of sleep she might.
That said, neither of my girls ever really took to the dream feed, so it's not a big deal if she just doesn't. They both slept pretty well at night, so it's just their natural preference. Babies are all so different!