If you make a new entry in fstab it will not auto-mount. Therefore you must reload / refresh the entries. A reboot will do this but that is not a friendly way to do it. A quick way to reload new entries in /etc/fstab (fstab) is to use the mount command:
How can I make the network boot before mountall in 12.10?
Sometime could happen that ubuntu try to mount fstab entries before network is up.
Look in /etc/rc0.d for the service, it will have S##service e.g. S35networking
Renaming it to S36mountall will make it load just after networking. Or make the number 99 and it will load last.