linux - can't get the right cron job timing -

i'm trying stuff automatically every 8 weeks, had open new user crontab one:

crontab -e 0 9 * */2 1-5 do_this_stuff # every 2 month on monday till friday @ 9:00 

this should job every 2 month on monday till friday on 9:00 am, not. doing job evey week once. don't it. i'm doing wrong?

running system latest debian.

regarding http://wiki.ubuntuusers.de/cron should run fine

the anwer is, cron can't job randomly on random day in month. had change crontab to: 0 9 1 */2 * do_sm_stuff -- runs every 2 month on first day in month

thank igor