Outlook - iCalendar invites come in without options to accept/decline
I have been working on iCalendar for quite some time now and after a long and hard effort I have an iCalendar format which is acceptable to more or less all versions of Outlook. The problem I'm facing is that some times clients complaint that they don't get options to accept/decline/tentative an invitation. I have been googling a lot on that but could not even find a hint which could point me towards a solution. I have verified the invitations on my computer and others computers too, on Outlook 2003, 2007 and 2010 and all of them seem to display thei nvite to me just fine, that is, with the normal options. I'm pretty sure the client have been facing these issues and they are not just complaining.
What I am looking for is some information on whether there is an Outlook setting which would force Outlook to hide accept/decline options for specific settings in my iCalendar text. I am not looking for someone soves this for me, if I even get a hint or pointers towards a solution I'm confident I'd be able to follow the trail.
Please contact if any of you have ever faced such an issue.
Thanks.
Answer
What I have observed is that when the icalendar is not valid, outlook does not display the usual buttons. in my case I had a dtend before dtstart and that was enough for outlook to not consider the invite as valid (though google calendar and outlook.com did).