[Plugin: WP Super Cache] Caching limited number of pages, not entire site

Hi people, thanks for your time. I’m running a WP 3.1 install on an Amazon EC2 small instance with a bitnami stack. The site is working fine and the plugin v0.9.9.9 is correctly installed.
My problem is that pages and posts are not cached, only some of it. For example:

cached version. non cached version (this is the full post).

On the cached page the plugin displays it’s status correctly, example:

<!– Dynamic page generated in 1.107 seconds. –>
<!– Cached page generated by WP-Super-Cache on 2011-03-05 14:42:42 –>
<!– Compression = gzip –>

but I have no such comments on the full posts or pages (not even the home page).

Ideas? I already tried to reinstall the plugin, cleaning everything in between. As a side note, I had W3 Total Cache installed previously on this site, but unistalled it and deleted everything before installing wp-super-cache. I would greatly appreciate your help.