apt/sources.list error

[brownh@hartford-hwp.com (Haines Brown)]

I'm running woody, but need to install a backport of postfix. So I
added to /etc/aptsources.list the line:

  deb http://people.debian.org/~hmh/woody/ hmh/postfix/

This is the back port source specified on the debian site, it was
recommended by someone, and I visited the site to ensure that the
postfix backport was actually accessible there. 

When I run & sudo aptitude update I get the error message:

  Reading Package Lists... 0%
  ...
  Reading extended state information... Done

  W: Couldn't stat source package list 
    http://people.debian.org hmh/postfix/ Packages 
    (/var/lib/apt/lists/people.debian.org_%7ehmh_woody_hmh_postfix_Packages)
    - stat (2 No such file or directory)
  W: You may want to update the package lists to correct these missing files

I don't understand this. Is it saying that the address I put in
sources.list is invalid? Does aptitude update require some kind of
switch if the repositories are mixed (stable and testing)? What is thi
file /var/lib/apt/lists/people.debian.org...? It does not exist on my
machine. Does it need to create this as a directory and is failing to
do so?

Haines Brown