My trainer and I disagree on using markers while teaching nosework. What are your thoughts?

My question concerns rewarding for an odor 'find' during NW. I am having a disagreement w/nosework trainer who is certified in NW, but does not have an obedience training background. My dog is conditioned to my verbal marker, and when I give it he instantly knows he's giving the correct behavior, and that he can expect a food or toy reward momentarily. Per my trainer, we are not to give direction to the dog during NW practice, but she apparently believes this includes verbally marking the wanted behavior instantly with my verbal marker. I say that this is not giving direction but is rather an instant payoff (followed by food reward). Trainer seems to think my verbal marker is a direction to the dog and therefore is a distraction. I disagree. Can you comment on this for me? Thanks so much. I'm about to order Andrew Ramsey's NW DVD (have ALL of Michael Ellis's and some of Ed's DVD's as well), but don't know if I'll find my answer in the DVD.