I installed WordPress Popular Posts months ago, but even after all this time I still get the "Sorry. No data so far" error.
I'm running version 2.3.2 of the plugin. My theme doesn't support widgets, but I put the wpp_get_mostpopular() template code in the sidebar, and I used the shortcode on a test page. I do have the wp_head() code in my header.php as well.
I dropped the two tables, deactivated, and reactivated the plugin just for fun. I've done a lot page visiting (while logged out), and I'm getting entries in the tables.
However, still nothing in the sidebar, and on the settings page, it also says "no data." Anything else I can try?