automounter doesn't automatically mount network folders

Binary package hint: autofs

let's say my NFS server (server1) is sharing the directory /export

I do a /net/server1/export from my ubuntu gusty gibbon and i get the error msg " No such file or directory"

This used to work on all ubuntu's beforel 7.04, 6.10 and 6.06 on my system.

i have uncommented the line "/net /etc/auto.net" from the auto.master and restarted the autofs service.

My system is a nis client. The automounter mounts my home directory from the NFS server without any problem. It's only the directories under /net/server1 that gives problems.