"rn -c -s" hangs after "echo -n" in csh

[M.S.Parsons]

Using csh on our 4.2BSD VAX 780, why does:

    echo "Unread news: "
    rn -c -s

Work quite happily in my .login, whereas:

    echo -n "Unread news: "
    rn -c -s

Causes rn to hang?

Please excuse if this has been mentioned before,
  Mike.