Loading data from external php

hey guys,

i just tried to figure out how to load data from an external php-file.
i tried to do it with crossdomain.xml file but it just works with external .swf to load in.
is there any tricky way to make that work ???
there always appears a security sandbox exception though i have located the crossdomain.xml in the root folder.
as i said there is no problem with external .swf but .php files.

any help is appreciated