obj.ttl not working ?

[Chris]

We are trying to get varnish to remove from its store all objects
older than 1 day.

Here's the vcl:

sub vcl_fetch {
  set obj.grace = 2m;

  if( obj.ttl > 1d)
  {
     set obj.ttl = 1d;
  }

  if (obj.http.Pragma ~ "no-cache"
    || obj.http.Cache-Control ~ "no-cache"
    || obj.http.Cache-Control ~ "private") {
    pass;
  }
}

It doesn't seem to work the objects just go up and up :-(

Varnish 2.0.1