gotoandplay in external swf.. problems

Hi,
Ive got a small problem with F8, gotoAndPlay .. small explaning ...

-I have the main SWF, that swf loading 6 externals swf with animations
-that 6 loaded externals swf.. is loaded to MCs (banner1, banner2...)
-there is a button in main swf,and if you pressed the button one of those 6 externals swf is suposed to play from the beginning
I use _root.MC.gotoAndPlay(1); script to do that

and now the problem,
In test movie (macromedia flash profesional > control > test movie) everything works fine, but if i run this movie in IE, Opera, FF, or just Flash player it doesnt work.... and doesnt work only this line... _root.MC.gotoAndPlay(1); nothing happens

any idea???

thx a lot

are the banners loading into flash ok aside from not playing? Also I assume when you use the term MC you refer to the instance name of the mc you load the swf in to?