deletes not syncing on touchdown

I am having a problem.

Often when I delete items in my touchdown inbox on one of devices, those deletes will not consistently synch with my desktop outlook or across other devices.

For example if I delete an email while on my tablet, that email will not always delete from my smartphone inbox.

Or sometimes I delete on my desktop, but my smartphone will still show the delete.

The "delete items on server" box is checked in touchdown settings...

Thanks