placeholder of the cube-side on init

Hi,

I'm trying to create an application where the path to the pano cube pngs is dynamically set. It works fine when I embed krpano with a static scene (using call and loadpano) but when i try to set the cube url as a variable of createPanoViewer, the placeholder doesn't seem to be taken into account...

var viewer = createPanoViewer({swf: 'krpano.swf', target: target});
viewer.addVariable('image.cube.url', 'panos/firstPano/pano_%s.jpg');

returns following error :

NetworkError: 404 Not Found - http://localhost/application/panos/firstPano/pano_.jpg