valid cron exprssions not allowed

I tried:
0 0 8-16 * * MON-FRI
and
0 0 8-16 * * 2-6

Both should allow "business hours" scheduling. It appears that it is the last element (day of week) that is not accepted, even though it is allowed here: http://www.opensymphony.com/quartz/api/org/quartz/CronTrigger.html