Not all cron jobs runs properly

Question

I have the big strange trouble - yesterday i have 3 my cron jobs working properly. But today - only 2. And there is a problem - i have all cron jobs using php like this:
/usr/bin/php5 /var/www/username/data/www/site.tld/cron.php >/dev/null 2>&1
But today i have mystic things:
1. grep CRON /var/log/syslog showing cron is running properly on this site
2. shell command /usr/bin/php5 /var/www/username/data/www/site.tld/cron.php working properly - script are working
3. BUT! I used ISPManager Lite as server-manager, and run cron job from it - i get Exited with error code - 255. Other cron jobs runs from ISPManager Lite normally.
4. Of course, when i apply script in shell by hands - it works; if cron do this work - nothing happened.

Any suggestions, please??

System: Debian, ISPManager Lite, PHP5.2.6-1+lenny8, Apache2.0

UPD1: Server Administrator email me:
resource held maxheld barrier limit failcnt
kmemsize 13355322 33677498 33554432 36909875 2644082
privvmpages 58616 127740 114688 126157 24442
Is it right, or my provider want more money?

Answer 1

Remove the redirect of standard output and error so you can see what's going wrong. Set MAILTO=somerealaddress@example.org at the top of your crontab if you don't get mail on the local system.

Answer 2

Alternatively, you can set it manually from the shell.

crontab -e

/usr/bin/php5 /var/www/username/data/www/site.tld/cron.php