Resistance to change of any kind is pretty much universal. If they have a way of doing things that seems to work for them, naturally they are not interested in investing time to learn your new way, even if it will eventually save them time. Maybe they don't consider the work you're saving them from difficult or time-consuming. But most likely, they just don't want to spend 10 minutes learning how to use your tool if they don't have to.
in reply to OT: Getting people to use tools
This kind of resistance can be seen elsewhere (using CVS, using CPAN modules, etc.), and I don't know any silver bullet to solve it. You can try winning them over one at a time, or your manager can tell them they have to use it. I've seen teams waste tons of time or use terrible tools because of unwillingness to try new things. Many won't change if they have a choice in the matter, but once they try the new thing they'll realize how silly it was to do it the old way.