SetInterval confusing mii please

Goog day peps

am gona make this quik and simple

the situation is i have a main MC that runs at 40fps and i have imported another standalone MC that’s when played on its own runs at 80fps twise the speed of the main MC and i have read and belive the SetInterval code was suppose to overide the framerate of the main MC which i have set to 40fps

So when i run/test my main MC with the 80fps MC also running inside the main MC everything runs at the same speed of the main MC which i set to 40fps and i Thought that SetInterval was a code that can make MCs inside a main MCs run faster than that of the main MC please i hope you understand

also sorry am a lite AS user but i know what i want too this is the code i was watching
fastFrames = function(){ myMovie_mc.nextFrame();
updateAfterEvent();
} speedyID = setInterval(fastFrames, 40); and i got it from here at kirupa the second line of example codes http://www.kirupa.com/developer/actionscript/setinterval2.htm

please help out i know theres a legend out there who understands

k,s inc :puzzle: