Let me guess, it's the one from PublishAmerica? There's been a lot of discussion over how they have often refused to make books returnable. Many of us have been curious about how their new return policy works in practice - there have been rumors that they don't refund the whole price, for example. You might want to drop in at the Neverending PublishAmerica Thread in Bewares and Background Checks if you have any detailed information on their return policy.
Unfortunately, there's a couple other obstacles to be overcome that make it hard to sell books from PublishAmerica. The first may be the price - it's a bit higher than many other trade paperbacks. Second is that PublishAmerica often doesn't offer bookstores as good a discount as other publishers, so sellers will make less money on each copy sold. Third is that PublishAmerica books are a mixed bag - some are excellent, and many aren't. With PA not making much of an effort to weed out the ones that aren't, bookstores are worried that they may get bad books, although an endorsement from Norman Mailer may be pretty helpful there. Fourth is the notoriously bad job their editors often do.
Anyway, good luck. With an endorsement like that, you may have better odds than average at getting it into bookstores.