Preloader question

I have a preloader that loads **all **the external.swf´s into a containerMC as they are called by various buttons. Now i´m trying to load another external.swf into a containerMC but this time without a button event. So i put on the main timeline of my main movie this As:


the problem is that the swf can be loaded into the containerMC but the preloader doesnt comes up, he does not display the precents loaded of that external.swf (without a button event) as he does when an external.swf is called by various buttons. I cant figure out why this problem occours. Any help?
tanks in advance