Cron jobs

I'm trying to run the cron jobs (notify.php, cmd.php, tags.php), however I get the following error :

Output from command /usr/bin/php5 -q /home/xxx/public_html/periodic/cmd.php ..

 

PHP Fatal error:  Allowed memory size of 8388608 bytes exhausted (tried to allocate 368640 bytes) in /home/xxx/public_html/inc/classes/BxDolClassifieds.php on line 2108

I have the memory_limit set to 32 MB, which should be MORE than enough!!

I have tried setting the memory limit directly in the 3 files(ini_set("memory_limit","16M");), and then it seems to work in the sense that I get no error
messages anyway. However, my cupid mails are still not generated, even though I have done the adjustments in the admin. Anyone got an idea?