I'm not sure what the issue was, after dorking around with it for a few hours I thought it would be quicker to just start from scratch. I reinstalled the base system it was expecting (RedHat 5.5, but I use CentOS) and it magically started making the calls again.

The only thing I can figure is that since this was a machine I was using for other purposes, I was keeping it updated. One of the patches since that release and now must have mucked with something that the script was using.

Like I said, completely bizarre. Thanks for the suggestions on strace (which I completely forgot about) and set -x (which I never even knew about).