Package folders / should be simple, but not working for me

I’m trying to move on from simple examples to a structured program package, but I can’t figure out what I’m doing wrong.
I think I’ve followed the instructions properly:
this fla does make a swf w/o compiler problems, but it does not execute the constructor.
this example is pretty stripped down. when constructed, devUtil should trace “devUtil constructed”. it doesn’t. I’ve tried several different files and folders and working custom classes, all with the same non-results

folder structure
devBase/src/devPak (devPak contains devUtil.as & devUtil.fla)

devUtil.fla doc class = devPak.devUtil
devUtil.as code:


package devPak {
    import flash.display.Sprite;
    public class devUtil extends Sprite {
        public function devUtil():void {
            trace("devUtil constructed");            
        }
    }
}

can anyone tell me what am I missing here?