can't access the form object in popup

[tsangkinyip]

Hi,

This may be an old question. I have a page where I would like to
include the name of the referrer file into the subject line of an
input field in the new popup window. However, the browser keeps on
throwing the error :Object not found". I've found that
newwin.top.document works fine...but once it gets down to "form" the
object becomes null. Can anyone explain the reason behind this, or
should I implement in a different way:

<a onClick="javascript:launchwin('../contact.html','....','....');
newwin.top.document.form.subject.value='testing';"><img src="..."/></
a>

Marco