SUNOS rmount to ULTRIX disks

[KARAGEOR%CTSTATEU.BITNET at yalevm.ycc.yale.edu]

I wonder if anyone out there had the same problem
        I am running a little net consisting of 1 decstation 5000/200
, 2 sun386i and 1 sun3/150. The problem is on NFS mounts of filesystems.
When the decstation mounts remotely on one of the filesystems of the suns the
systems it works like a charm. When i am trying to mount a SUN subdirectory
to  Decstation filesystem then ultrix responds with "RPC failure: Invalid client
credential."
     Any insight anyone?

the decstation is running ultrix 4.1
the sun 386is run sunos 4.0.1
the sun 3/150 runs sunos 4.1.1

        Attempts that have already failed :
removed the "-i" from "mountd" :Same problem
included all hostnames and internet addresses into yellow pages but did not
delete the server's hosts file.
copied the "rpc" file from the suns to the server and made it public through
yellow pages (NIS)(sic)(SICK!).
rewrote the "exports" file without tabs.
PS. the decstation is the YP server.

                Thank you
        Angelos Karageorgiou

karageor_ang at ctstateu.bitnet
karage at cmx.npac.syr.edu