mcs:
Seeing that you haven't had a response in 7+ days ... I'll try to help. I use ATI (version 9) myself, but never yet across the network, only to another partition or a second HDD on the local PC that I boot the rescue disk from. Then I reboot the PC normally and copy the TIB to the NAS.
I have a feeling the TIB file is marked "hidden" or has some other special permissions on it. Another possibility is that ATI has created its own "vault" within which the TIBs reside. This would allow you only to view the "vault" (whatever that looks like ... not sure of the file extension or encryption and compression used).
Try
1] from ATI do a "check archive" to confirm there's nothing wrong with the file created. (Always a good idea anyway.)
2] Boot the NAS with a LiveCD (your favorite ... Knoppix, Ubuntu, whatever) and search for the file that way.
Hope that helps point you in the right direction.

Georg