I also had Topsy retweet installed on 2.9.2 and worked fine. The only plugins that I changed out were a comment form and copyright notice at end of posts.
The form and copyright plugins I was using before didn't affect the topsy button at all.
The theme I downloaded before and modified was Celestial Aura by dkszone and I restored the original theme and reworked the prior mods I had so the only thing I can think of being an issue is the wordpress and button but perhaps there is something I am missing. The site is http://bibliophilesretreat.com After I downloaded topsy, activated it, and reworked the settings page, the posts are still blank where the button should be. My Add this button works fine but it's nice to have both buttons.