I solved the problem disabling php safe mode. Cache is working but still in admin panel WP Super Cache Settings -> Contents is shown:
WP-Cache (0KB)
0 Cached Pages
0 Expired Pages
WP-Super-Cache (0KB)
0 Cached Pages
0 Expired Pages
Also, every time i refresh the page, it is shown the new time in page source code in debug mode like this:
<!– Cached page generated by WP-Super-Cache on 2011-04-06 18:28:52 –>
And it is shown without debug mode:
<!– File not cached! Super Cache Couldn’t write to: wp-content/cache/supercache/sitename.ru/18575238494d9c85897e70b3.11755363.tmp –>
The wp-content/cache/supercache/ folder has 777 rules and it is empty.
So cache doesn’t work. What is wrong?