How can I get reviewers on amazon and lulu.com?

I've talked to my audience, shared on FB, linkedin, xing, viadeo, apsense, twitter, whatever social network you can think of...i promised my readers to provide them with a free pdf copy...some people have read my book and like it, why am I not getting any more reviews??? What am I doing wrong? I can't afford paid reviews at the moment, but i definitely need more reviews...any advice welcome...please read the part above before responding and please NO SPAM, thank you.