I have a user who is sometimes missing calendar appointments on their iPhone. Their iPhone is hooked up to an Exchange account via Active Sync. I thought at first the user was deleting it from their Outlook or iPhone, but I finally saw the problem today. The calendar item was in the users Outlook but not on his iPhone. Every other appointment I looked at was sync'd up fine. I was able to add new appointments to both iPhone and Outlook just fine. I finally turned off the calendar sync on the iPhone and turned it back on. Once I did the missing appointment re-appeared. Any ideas what could be going on? I tried to replicate the problem but I am unable to replicate it.