AIX 3.1, nfs mount trouble

[Scott Holt]

I am having a bit of trouble getting a mount working on a 540...here's
the specifics:

	Server: Sequent Symmetry, Dynix 3.0.17
		name, hydra.gatech.edu
	Client: 540, AIX 3.1 (2002)
	  	name, edison.gatech.edu

The Sequent seems to have its exports right - edison.gatech.edu is a
member of a netgroup to which the file system (/ocs1) is exported.
However, when I try to mount /ocs1, I get the following messages:

mount: server hydra.gatech.edu no responding: RPC: Authentication error;
why = Invalid client credential
nfsmnthelp: hydra.gatech.edu: Permission denied
mount: giving up on:
	hydra.gatech.edu:/ocs1
Permission denied


The entry for /ocs1 in /etc/filesystems is

/ocs1:
	dev		= /ocs1
	vfs		= nfs
	nodename	= hydra.gatech.edu
	mount		= false
	type		= nfs
	options		= fg,hard,intr

The message leads me to believe that one of the two machines is trying
to use secure NFS - which I know is not true (or at least should not be).
BTW: the same file system is exported to a 930 on the same network and
that mount works fine.

I'm perplexed, any clues?

Thanks,
Scott