Ron -- just to be clear:
The plugin DOES work with 4.0, right?
I contacted technical support. They said that mod_rewrite is enabled. According to them, Apache "is configured in such a way that it does not need to be restarted."
I've double-checked htaccess and the Rewrite Engine is on. Not being the best with servers, I'm kind-of taking their word for it. I have, however, used mod_rewrite for other non wordpress issues on this server and have had good success.
Just not this time.
I've used your plugin on a Wordpress 3 site with great success, which is why I'm wondering about this being a Wordpress 4 issue.