[Plugin: WP Super Cache] Tester: The pages do not match !

Hello.

I am having a hard time to install WP-super-cache V0.9.9.6 (the same with 0.9.9.5 although it worked once only before I upgraded to 0.9.9.6).
I tried everything possible but the plugin does not work.
Each time I try to use the ‘Tester and contents’ tab, and click on the ‘test cache’ button, the answer is the following (translated from french):
The pages do not match ! The dates are different or have not been found.

If I go to the wp-contents/cache, I don’t see the super-cache directory, so it seems that it is not working properly.
however I don’t know what to do to make it work.

It doesn’t matter if I use the mod-rewrite mode, phph or legacy, all fail the same.

The files advanced-cache.php and wp-cache-config.php are located at the proper place and contain the proper locations.
The .htaccess files are properly set, and wp-content is accessible in 777 permissions.

Thanks for any help in that matter.

Daniel