Problems with Janet and Bitnet

[SLG6M%USU.BITNET at WISCVM.arpa]

Help!  I have been trying without success for the past two weeks
to send a mail message to Nigel Holder at Marconi Research.  I
am connected to Bitnet, which allegedly has the capability to
send mail to JANET via a gateway at a Bitnet node called UKACRL
in London.  It gets to London via Bitnet OK, but then I keep getting
"YF21 at UK.CO.GEC-MRC.U Is an invalid assress. No delivery made."
mailed back to me?  Any ideas a) what's going wrong here, and b)
how do I send a message to Nigel?

The message that I wanted to send to Nigel is that I am interested
in the public domain version of talk for System V unix that he advertised.
However, I recall he said something about it being placed on a file
server (one I don't know how to access), but I think it would be
easier just to mail it to me at USU.

                --David Barts
                  SLG6M%USU.BITNET
                  Utah State University, Logan, Utah, USA