NFS mount failure - why?

[Oliver Elphick <olly@lfix.co.uk>]

nfs-kernel-server version 1.0-2

/etc/exports: 
/usr1   louise(rw) elsie(rw) sarah(rw) rover(rw,no_root_squash)
192.168.1.105
/usr2   louise(rw) elsie(rw) sarah(rw) rover(rw,no_root_squash)
192.168.1.105
/usr3   louise(rw) elsie(rw) sarah(rw) rover(rw,no_root_squash)
192.168.1.105

mount from sarah of /usr2 and /usr3 succeeds but mount of /usr1 fails:

# tail /var/log/syslog

Feb 24 12:24:43 linda rpc.mountd: authenticated mount request from
sarah.lfix.co.uk:804 for /usr1 (/usr1) 
Feb 24 12:24:43 linda rpc.mountd: getfh failed: Operation not permitted 

Can anyone say what this means and how to cure it, please?

-- 
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver
GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839  932A 614D 4C34 3E1D 0C1C

     "Thy word is a lamp unto my feet, and a light unto my 
      path."           Psalms 119:105