I have a bunch of users who have a have a Group/public calendar in our Exchange 2010.  These users can only get to their exchange accounts through OWA.  When they log in , using IE, they can create and edit their appointments in the Group/public calendar just fine.  the issue is when they go to set a reminder, they cant do it.  The box you check is grayed out so you can not check it.  When I went to take a look I gave myself owner rights to the calendar so I could make all the changes I wanted to. however I the check box was still grayed out.  I also was able to check the reminder box when I added a appointment to my personal calendar.  I finally went into my outlook to take a look at this and it worked just fine.  Is there a feature I need to turn on to allow this or does OWA just not allow this for public calendars? 

Software/Hardware used:
Exchange 2010 on VMware