Sorry to bust in on this thread but I am having the same issue... I have a Nas4Free Samba share with 1.8TB of music files. The share is mounted to the Airtime installation using mount with the -t cifs option.
When I run airtime-import --watch-add mynasmount i get nothing, it simply returns to the prompt immediately.
Any help on this would be greatly appreciated, we would love to use your software!