Controlling main swf from loaded swf

My root swf loads an external swf using the following code:

on (release) {
	_root.c1_mc.loadMovie("mask.swf");
}

…where c1_mc is the instance name of an empty movieclip container.

Now, i tried loading a second swf into the root swf via a command in the first loaded swf:

_level0.c2_mc.loadmovie("bio.swf");

…where c2_mc is the instance name of another empty movieclip container, but it doesn’t work.

Is there something wrong with the code, or does flash not support this?