Write Permission Error

I have transmission-deamon running and it's giving me the error Permission Denied: /mnt/RyNet/Downloads/the-torrent/some-file.ext

So it cannot write files to the download directory:

ryguy@MPU /mnt/RyNet $ id debian-transmissionuid=120(debian-transmission) gid=132(debian-transmission) groups=132(debian-transmission),117(sambashare)ryguy@MPU /mnt/RyNet $ ps aux | grep transmis120      16184  0.2  0.3  57724 12644 ?        Ssl  22:17   0:11 /usr/bin/transmission-daemon -f --config-dir /var/lib/transmission-daemon/inforyguy@MPU /mnt/RyNet $ ls -alhtotal 100Kdrwxrwx--- 16 root  sambashare 4.0K Apr 15 21:36 .drwxr-xr-x  5 root  root       4.0K Dec  4 08:20 ..drwxrwxrwx  4 root  sambashare 4.0K Apr 20 05:30 Downloads

But, I have the download directory permissions set to 777, owned by group sambashare.
The transmission-deamon is running as debian-transmission user/group and the debian-transmission user is in group sambashare.

Even stranger, when I set the debian-transmission user's shell to /bin/bash and login via su, I can easily issue commands such as touch /mnt/RyNet/Downloads/testfile with no errors and it creates the testfile just fine.

So, why can't transmission-deamon write files to the download directory?