PHP and wml problem

Hello, I have a problem with my php files. Here's how it goes: I use Sablotron (a php extension) to parse my XML file in order to view the result on a wap browser. The parsing goes well and the result is good but the browser does not understand that it's a WML file. If I copy the result of the parsing and make a *.WML file with it, verything works fine. If I read the *.PHP file, all the cards are displayed on the same screen and the browser doesn't recognize the title and the timer... Does anybody have a solution? Thanks