I've set up a few activities on our site, one that targets returning customers and another that targets new visitors. The number of entrants seems very low. (Only 1k over the course of a week or two).
I'm concerned that this means that the tracking is not setup correctly. Since both of these are experiments on our landing page/visible on many different pages, I would expect the number of entrants to track closely to the total number of sessions that we see from Google Analytics.
Google analytics for the same time period indicates that we should have had 25k returning customers. The experiment was a simple A/B that swapped out the html offer in the upper right of our landing page. The offer is also available throughout the site on search results pages and product category pages.