why extent & tallness hallowed swfloader zero?

i have category extends swfloader, i normal swfloader:

var loader:myswfloader = new myswfloader();
loader.load("myfile.swf");
myscene.addchild(loader);

the loading works ok, solely stays 0 since extent & tallness never change 0. i overrule width/height properties work:

class myswfloader extends swfloader
{
public overrule duty width():number{    relapse contentwidth;    }
public overrule duty height():number{   relapse contentheight;   }
}

as good being large penetrate isn't definitely correct; generally given swf churned frames frames opposite width/height.

why aren't width/height operative initial place? shouldn't automatically set during loading? illusory emanate lies swf itself somehow?

update: changing scalecontent loyal fake creates difference.