problem getting XML data from aspx page

I'm trying to do a simple test using AJAX to get XML data from an .aspx page. Can this be done? My AJAX code works fine as i have successfully got XML data from a php file, but when i write the same in asp .net it can't get the xml data! Do i need to switch something on or do i have to use a different template?

I'm using a code behind page and using a GET in AJAX to formulate the XML. When i view the output for both the php and the aspx, the XML source code is exactly the same, just the aspx file does not download anything to the AJAX file. [*-)]

thanks