When it doesn't work do you get an error? Let's concentrate on your site and not what UPS sent you... you say it doesn't work... do you get any rate returned? no rate? an error?
General documentation from UPS won't help me debug the precise issue with your implementation. Please give specific information about what you see and I can look into it further. What address are you using? I'd want to use a similar address also for testing.
If you want help debugging I'd probably need FTP access. You can turn on debug mode from the admin panel and then visit the checkout_failure.php page after the failed shipping quote to see the full message returned from UPS, which will usually help shed some light on the exact problem.