Hiya Kim,
I only used the dream feed a few times so I'm no expert but this is what I remember ...
Ciara wouldn't latch on if she was fast asleep. I had to listen (at the door
) for her starting to fuss/move around indicating that she was nearing the end of a sleep cycle. I would then go in and offer the dream feed and she would take it. However, if I went in too early she wouldn't latch on at all and I'd have to try again.
The dreamfeed didn't work for us so we only used it a short while, so that's about it for my advice I'm afraid.
HTH a bit and good luck