[FMX] recording time and date

i have a _parent.swf that loads a _child.swf using the loadmovie command. i have variables able to be passed back and forth, np. my problem is that i need to be able to record when the user started the _child.swf and when he(she) ended and went back to the _parent.swf. i have tried this method to no avail:

onClipEvent (load){start = new Date();} 

on the first frame of the _child.swf . start being a var to dynamic text located w/in the MC

on frame 5…i have this code:

onClipEvent (load){end = new Date();}

end var also points to a dynamic text field

but what happens on frame 5 is that the original date gets erased, as does the start var.

is there anyway i can keep both timedates ???