HTTPGet subject line

I'm using HTTPGet to generate a dynamic subject line which works fine when I use this code:

 %%=HTTPGet("http://sandbox.site.com/newsletters/daily_subject.php")=%%

But the following does not work. Actually, it works in the preview but not when the email is sent:

 %%before; httpget; 1 "http://sandbox.site.com/newsletters/daily_subject.php"%%

I would prefer to use the second because I only want to make one http request. Any ideas?