My iPad syncs reminders both ways, work colleague's only one way

I can sync reminders to and from 2nd Generation iPad using iOS 6.1.3 and Outlook on Vista PC via ActiveSync account. Work colleage has 4th generation iPad but using same iOS, ActiveSync settings as far as we can tell but can only sync from PC to iPad. Reminders set from his iPad do not show in Outlook on his PC. Why not? How can we troubleshoot? Not interested in location based reminders so we still have Reminders Setting turned to "ON" in Exchange ActiveSync within the Mail, Contacts, Calendars settings area.