I would do an ASCII EXPORT of your Contacts from your BB. Open that new .csv file and compare the field headers with what you're trying to Import. I've found if you move, delete or modify any of those field headers you will get errors when you try to import.
You have Contacts in your BB and yet none exported? Double check the setup in the Advanced section and make sure you're moving things in the right direction.
sorry... In DM, Synchronize, Configuration, Configure Sync..., select Address Book and then Setup, ASCII Importer/Exporter, here is where you choose which direction to sync. With ASCII you can only go one way at a time. I'm using DM 4.3 but I think it's a similar path in the newer versions. I've used the newer ones but can never get a good backup so back to old 4.3.