Drag function not working in a external.swf

Hi, I have a swf. called “menu” that load a external .swf “sitios” with the conteiner method, and that movie have a drag button inside a movie clip called “sitiosmov” it works well draging that movie clip, but when “menu” loads “sitios” the drag button doesnt work, I check the route but I cant find the problem this is the code:

on (press) {
setProperty("/sitiosmov", _alpha, 30);
on (release) {
setProperty("/sitiosmov", _alpha, 100);