Usually a sign that the device hasn't enterprise activated correctly.
1) Does it receive email correctly?
2) What happens when you try and send mail from the device - i.e. to
rather than to a GAL Listed address?
Oh and suggest you post BES related / linked question in
BES Admin Corner - BlackBerryForums.com : Your Number One BlackBerry Community this forum as the BES gurus all hang out there (apart from when they're all getting wasted care of Jim 'n' Mike in disneyland!!)