Now, I'm not someone adept with social interactions, but even I am familiar with the old adage, "You can't expect something for nothing."
If you're not going to pay someone for their work, at least come up with something to reimburse them for their time. For example, write a review or give them a powerstone (if they have a novel for you to do that), or maybe reconsider your 'free' statement altogether, and pay them something for their efforts.