/msg command does not work

I'm running drupal 4.7.x on an IIS 6.0 server with PHP 5.1.4.

The /msg command does not appear to work. For instance, I type "/msg username this is a message" and nothing ever appears in the chat window of the intended recipient.

Darren, if you look into this, your account is still active on my site.

If another developer looks into this, please send me a message if you need an account on my site to test with.