Your server is probably defaulting to version 2. Version 2 is included by default in the kernel modules. The problem is AUFS doesn't support version 2. From the aufs docs:I've got it working by forcing version 3 ( mount -t nfs -o vers=3 etc)
You might get away with a version 2 mount if it's outside of the layered filesystem (e.g. /mnt/home/folder). I don't know about Lucid 525, for Fatdog64 AUFS is configured to handle (v3) nfs mounts within the layered filesystem.• NFSv2 is not supported. When you mount the exported aufs from your NFS client, you will need to some NFS options like v3 or nfsvers=3, especially if it is nfsroot.