okay ... if there are no windows machines in your network then that may be part of your problem, as there is no domain for the nas and your ubuntu box to join.
although there are no windows machines in your network, you are using a windows protocol to connect to your nas device, so you have to play by windows networking rules.
now, in this file, you'll have to enter the following data. but keep in mind you're going to have to change the specifics to meet your situation's needs:
sudo aptitude install samba
sudo /etc/init.d/samba stop
sudo mv /etc/samba/smb.conf /etc/samba/smb.conf.template
sudo touch /etc/samba/smb.conf
sudo nano /etc/samba/smb.conf
now ... be sure to change "YOUR_HOSTNAME" to a name unique to your ubuntu computer, and change YOUR_WORKGROUP to a workgroup name common to both your ubuntu computer and your nas device (most likely mshome).
; General server settings
netbios name = YOUR_HOSTNAME
workgroup = YOUR_WORKGROUP
announce version = 5.0
socket options = TCP_NODELAY IPTOS_LOWDELAY SO_KEEPALIVE SO_RCVBUF=8192 SO_SNDBUF=8192
save the file and exit.
now, don't forget to modify the permissions on your mount folder. for example from my howto:
and finally ... restart the samba daemon:
sudo chmod 777 /media/sharename
then see if you can mount again.
sudo /etc/init.d/samba start