Why isn't my auto proxy setting working for Safari 5.1 in Lion? I have a SOCKS proxy listening on 7070 at localhost.

Here is what my proxy.pac file looks like (to keep the test simple, I just return SOCKS proxy for all urls):

function FindProxyForURL(url, host)
{
   return "SOCKS 127.0.0.1:7070";
}


This doesn't work in Safari or Chrome. However, for other native apps like Twitter for Mac and Dropbox, this works fine.

I'm getting around it by using Firefox with the Autoproxy plugin, but I would like to use Safari. Why isn't it working?
Setting the file again under Automatic Proxy Configuration after entering any junk URL seems to re-read the file for me.