Drawing anti-aliased lines using the GD library

I was following an article on a website earlier, and although it
outputted the pie chart for me perfectly, I want to make it anti-
aliased somehow. I have linked to the specific article below just in
case you wish to replicate for testing the anti-aliasing. I found the
GD function, imageantialias() but I've tried setting it to true at the
top of the code just after the imagecreate() function - but to no
avail.

Article: http://www.talkphp.com/showthread.php?t=1629

Somebody please help me!! I'd really love to get the anti-aliasing to
work as it'd then be perfect for what I need it for. With it looking
rough at the moment it looks naturally unpolished which is no good for
my client

Thank youu in advance!