Google maps with KML problem

[Thanh Truc Ho Nguyen]

Dear all,

Currently, I want to get the public transportation from one place to
another in Japan in KML file format. I use the following request for
route from Tokyo to Osaka:
http://maps.google.com/maps?f=d&hl=ja&ie=UTF8&dirflg=r&saddr=tokyo&daddr=osaka&output=kml
But I receive a KML file with no content (size = 0). I try this
request in the browser but not for kml file, it works. I've read but
do not get any limitation about KML file. So I don't know why the
first request does not return a file with content.

Can you tell me what is the problem?
I'm very appriciate for your help.