Communicate with Javascript

Hi,

I am trying to send some information to a javascript function on the same html page as the swf file is in. I used the tutorial here on Kirupa but for same way it doesnt work.

ExternalInterface.call("fillForm('"+ l.x, l.y +"')");
ExternalInterface.call("fillForm", l.x, l.y);

These are the variations I tried. Anybody knows what I am doing wrong because its almost the same as the tutorial.