I've got a BES Express and three attached devices. Everything is working fine on these devices except when I delete items from the mailbox, they will appear on the device, and even when I read an item on the mailbox it still shows as unread on the device. Bi-directional synch is setup and they do apepar to be working fine, except for these two little issues.
Go to the options on the device, go to Service Books, and delete the "Desktop [SYNC]" service book. Once it is deleted, click the wheel in and hit "UnDelete". This will force a re-enterprise activation. Try it out after this. Wait a hour after it activates to make sure too ;)
"I take off my robe and wizard hat...."