procmail: Error while writing to "/

Here's my .procmailrc

        ##########################################################
        # Let's start filtering out "from"s - I wonder if I have #
        # to go from a black list to a white list! :-(           #
        ##########################################################
        :0 c
        {
        VERBOSE=yes
        :0
        * ? /home/dcw/bin/checklist.pl "$SENDER" $MAILDIR/whitelist

        :0 E:/home/dcw/FILTER.LOCK
        * !^(Original-)?(Resent-)?(From|Sender):.*(root|postmaster|abuse)
        | (cat $MAILDIR/fromlist;  echo $SENDER) > /tmp/list; sort -u < 
/tmp/list > $MAILDIR/fromlist
        VERBOSE=no
        }

Here's the logfile:

procmail: [14994] Wed Nov  6 16:53:42 1996
procmail: Executing "/home/dcw/bin/checklist.pl,From: 
asp1627(_at_)is(_dot_)nyu(_dot_)edu,/home/dcw/Mail/whitelist"
procmail: [14994] Wed Nov  6 16:53:42 1996
procmail: Match on "/home/dcw/bin/checklist.pl From: 
asp1627(_at_)is(_dot_)nyu(_dot_)edu /home/dcw/Mail/whitelist"
procmail: Error while writing to "/_Hg3Ggsdws133"
procmail: Error while writing to "/"
procmail: Assigning "VERBOSE=no"

From asp1627(_at_)is(_dot_)nyu(_dot_)edu  Wed Nov  6 16:53:30 1996

 Subject: test
  Folder: spool/inbox                                                       347


PS Is there an easier way to say "if such-and-such program doesn't
return a value"? I tried !? and ?! but neither one seemed to work.

--
 David C. Worenklein                                       GREENWICH   CAPITAL
 Operations Support                                        M a r k e t s,  Inc
 =============================================================================
 phone: 203-625-2945                                                      ====
 fax:   203-629-2535                                                      ====
 e-mail: dcw(_at_)gcm(_dot_)com                                                 
     ====