External imageblock size help

I am having trouble getting the exactSize or maxSize options to work.

My randon image does load but it always loads the full size image which wastes bandwidth. I want to use exactSize or maxSize so that it will load one of my Target sizes instead.

Here is the line that is working but not as efficiently as I would like.

<p><?php@readfile('http://www.unity.pvt.k12.ia.us/gallery2/main.php?g2_view=imageblock.External&g2_blocks=randomImage&g2_show=fullSize&g2_maxSize=440'); ?></p>