[jQuery] why does $('.myDiv', top.frames[0]).hide() not work?

[jQuery] why does $('.myDiv', top.frames[0]).hide() not work?


I'm totally not getting it... but you might, I hope :)
I appended an iframe:
$('body').append('<iframe>...etc</iframe>');
The iframe source has jquery in the header and it works.
now I want to do something in that iframe, like hide a div. I want to
do this from the top.frame...
$('.myDiv', top.frames[0]).hide();
but, it doesn't work!??!?
I'm lost. Been googling, all I find is stuff about getting stuff to
work in the parent frame - why wouldnt the same work for a child
frame?
THanks for pointers! much obliged...