su to bin on RS/6000

[Judy P. Halchin]

    I'm trying to compile cnews on an RS/6000, and the installation
instructions would have me login as or su to bin to run some of the
installation scripts.  When I try to su to bin, however, I get the
following message: "Cannot su to "bin": Missing file or filesystem".
I've checked that all users have permission to su to bin.  When I
try to login as bin, it lets me get through the password but then
dumps me off.  bin is set as a login user.  Any suggestions?
   Thanks,
      Judy Halchin
      Academic Computing
      Eastern Illinois University
      cfjph at ux1.cts.eiu.edu  (or cfjph at bogecnve.bitnet)