NFS4 strange anonuid/anongid values

[disk91]

New element :
After updating my /etc/idmapd.conf with the following elements:
[Mapping]

Nobody-User = myuser
Nobody-Group = mygroup

then restart /etc/rc.d/nfs restart

now, the mount are all associated to myuser:mygroup ... anonuid and anongid seems to no taken into account by the system ... could you explain why ? I have different mounts and I need to use different user for each mounts.