Child doesn't resize

Hello,

I have a problem with child's in a movieclip

I try to resize the movieclip "ImageIntro" but the childs inside it, do not resize

My code

var stageWidth = sym.$('Stage').width();

sym.getSymbol("TotalSite").$("ImageIntro").css("width", stageWidth-80);

if i try to resize directly a child, it work, but because I have more than one child i want to resize the movieclip that include all of them...is someone know a solution for that ?

A precision, the "ImageIntro" clip resize, but not what is inside of it

Thank you and excuse my english