Problem with external swf

In the current flash project im working on I load an external .swf into the main .swf, the external .swf contains sound loops and movieclips which they are attached to. In the main .swf there are buttons which trigger the sounds to stop and start.
the problem im having is that the sounds wont play when the button is pressed, when everything is in one file it all works fine, so i believe the problem is to do with the reference to the external file.

here is the code used…

// code for loading external .swf
	_root.libary = "libary.swf";
	loadMovie(_root.libary, _root.container);

// code for referencing the sound in external .swf from main .swf
            _root.libary.sound_libary.sl_block1.sl_block1_1.drum001.start(0,999);
            // long path to the movieclip the sound is attached to.

what would be the correct way of referencing to the sound in the external .swf?