[Samba] username map script never runs

[CG]

I'm new to Samba, but have been reading manuals, faq's, and list archives and 
have been googling for a week. I can't figure out what's going on. Here's the 
situation:

I want to use winbindd to unify authentication for the users who have both 
domain accounts and linux accounts and who use pop3/imap on my Linux SMTP/POP 
server.

Security is set to ADS, and I have PAM authentication functioning, but a 
feature I was depending on isn't working. I've tried both "username map" 
and "username map script" to map AD usernames to unix usernames. I was hoping 
that either one of those options would provide me the glue to attach one to 
the other. Winbindd doesn't use those options, though.

Here's a little "username map script" that I cooked up to check to see if it 
was being called.

#!/usr/bin/perl

if ($ARGV[0] =~ /Foo Bar$/i) #checks for user "Foo Bar" with or without domain
{
  print "foobarbaz"; #prints unix username
}
open FOO, ">>/tmp/foo.log";
$date = `date`;
$date =~ s/[\r\n\f]+//g;
print FOO "$date Ping!\n";
close FOO;

/tmp/foo.log records no execution requests...


Help!

CG