Syslog:
edit:
mainproblem is still the path to php binary, i tried /usr/share/php which is written as open_basedir by default. you wrote /usr/bin/php, should i add this to open_basedir?
Where did you get that cron job from? It's completely wrong!
First of all, there is no php bin at /usr/share/php. Do a ls and see for yourself.
Second, it really doesn't help to have "> /dev/null 2>&1" while trying to debug! Google what this does, and you'll understand.
By the way: debian has a default cron for cacti which works perfectly.