sshfs is not mounting automatically at boot, despite /etc/fstab configuration

Setting up some Ubuntu (13.04) workstation, I am trying to have a remote filesystem mounted (over ssh).

The current config

• I created user someuser and added it to the fuse group

• My fstab entry reads like :

  sshfs#someuser@remote.com:/remote_dir  /media/remote_dir/   fuse    auto,_netdev,port=22,user,allow_other,noatime,follow_symlinks,IdentityFile=/home/someuser/.ssh/id_rsa,reconnect     0       0

from my understanding :

• auto : is explicitly asking for the remote fs to be mounted at boot
• _netdev : wait for interface to be up before attempting to mount
• user : allow any user to ask for this specific remote location to be mounted (useless in the perspective of the root user automatically mounting it at boot)
• allow_other : will allow any user (in the fuse group ?) to access the mounted fs
• IdentityFile : points to the private key paired with the public key added in the /home/someuser/.ssh/authorized_key of the remote machine.
• reconnect : Not sure... Will attempt to reconnect if the connection is lost ?

The problem

• At boot, I log with someuser, fire up a terminal, and /media/remote_dir is empty.

• But from the same user (or the root), I can mount it just typing :

  mount sshfs#someuser@remote.com:/remote_dir

  It is also auto-magically mounted if I click on remote_dir in a file browser.

Any clue regarding what could be missing ?