iframe and session

[Timmy]

Hi group, I've inherited some code which has a menu page
with an embedded iframe which displays the page
corresponding to menu clicks. i was attempting to pass a
session variable into the iframe page. sadly, it seems
that the page displayed in the iframe and the "hosting"
menu page are different session. i discovered this by
placing response.write(session.sessionid) in both pages.
why is this? is there a way to make the iframe page part
of the original session?
thanks for any thoughts...