It seems like every time I struggle with making a call that doesn't go anywhere, it isn't in the code at all, it's a proxy page issue. I noticed in your example that you are using machine names as opposed to domain names. That could be part of your problem.
A lot of the examples include a proxy subfolder relative to your project, but I have had no luck with that myself. Any time I have to use proxy pages, the only way I seem to get my code to work is to move it from my local machine to my test server. I have a proxy page configuration on it for all maps on that server. Other people don't seem to need to do this. I don't know if it has to do with our firewall settings or some other configuration.