Trouble scrolling a window with scrollBy( ).

[BGC]

I'm attempting something like this:

win1 =
window.open("pop_up.html","_blank","width=325,height=272,top=0,left=0,scrollbars=0,resizable=0");
win1.window.scrollBy(100,50);

I've done this before when instead of "_blank" I had a unique name there for
each popup I wanted to open.
ex.
win1= window.open("popup.html","ww1", ........
win2 =.........................................."ww2", ..........
etc. etc

Now I want one function you pass a filename and it will open a new popup
window each time by using "_blank" instead of a unique name for each popup.
I can't see why the top example won't work but it doesn't.

It would seem to me that win1 would reference the latest popup opened and
the scroll would apply to that window, but nothing is happening. Any ideas
would be helpful.

Thanks,
BGC