Thanks for your reply and yes you are correct in your assumptions.
Currently using the appointment writer, but got the same error with both
options anyway.
I am using the exchange admin account, but I have edited its permissions
to remove the explicit deny, so still a bit confused.
That said, if I dont need to confirm that function is working, then how
can i confirm that the GA cal items are being written back to exchange
correctly? Doing an explicit lookup for any items I have created in GA
dont show up in exchange.
thanks
tony