(lucid) autofs had a strange behaviour with paths

Binary package hint: autofs5

Hello, (sorry for my english, I will try to make it clear, french here)

I'm upgrading my workstations from karmic to lucid 32bits and I've got a strange behaviour with autofs.
The home directories (on my.debian.lenny.server:/home/net) are automounted via autofs after the client authenticate to ldap directory.

On the client, I created in /home a symbolic link (net) to /net :

(administrateur is the local account on clients)
administrateur@cyb22:~$ ls -all /home/
drwxr-xr-x 3 root root 4096 2009-11-09 09:25 .
drwxr-xr-x 23 root root 4096 2010-07-13 09:07 ..
drwxr-xr-x 41 administrateur administrateur 4096 2010-07-12 12:26 administrateur
lrwxrwxrwx 1 root root 4 2009-11-27 16:08 net -> /net

And here are the maps :

auto.master :
/home/net /etc/auto.home

auto.home :
* -fstype=nfs,hard,intr,nodev,nosuid,nonstrict,rsize=8192,async my.debian.lenny.server:/home/net/&

Each user's directory is created on the server before first mount by the client, with a Desktop directory containing a link to a public share which is mounted via fstab. On karmic, the home directory is mounted correctly and populated with missing files on first mount. It was perfect !

On lucid, it's less evident.
With the same automount maps, it doesn't work (error in syslog) :
Jul 13 16:42:10 cyb22 automount[958]: do_mount_autofs_indirect: failed to create ioctl fd for autofs path /home/net
Jul 13 16:42:10 cyb22 automount[958]: handle_mounts: mount of /home/net failed!
Jul 13 16:42:10 cyb22 automount[958]: master_do_mount: failed to startup mount

If I modify /etc/auto.master from :
/home/net /etc/auto.home
to
/home/net/ /etc/auto.home

It works, but the home path is strange :
On the client I've got the home directory side to the Desktop directory (one level is missing in path). In fact, the client populated the user's directory created by the server with another user directory. So I have not the link to public share on the desktop of the client, but in a Desktop directory in /home.

So on the client :

user@cyb22:/net$ ls
user Desktop

And on the server :

root@server:/home/net/user#
user Desktop

Feel free to ask further informations... Perhaps the / needed in auto.master could explain problems encountered by other people, I don't know, or I missed something ?

Have a nice day.