She might just be a picky eater. I've had one of those and I've had several that never met a food they didn't like. Fortunately, the two dogs I have now are of the latter persuasion. If she's not eating enthusiastically (and you're not feeding her more than she really needs), it may just be that she's not particularly fond of that food.
I've been using Total-Zymes (digestive enzymes) and Total-Biotics (probiotic) for a few months with my dogs, and just started using them with my cats too. They're not cheap ($65.99 for both on amazon.com), but the last containers I bought lasted me about 3 months: