Additional info to the answers above : An Iframe is a kind of "browser inside the browser". As is, you can only fill it with a well formated HTML full page with an header and a body.
If you want to use another container like a DIV, you should fill it with HTML code without HTML, HEADER and BODY tags (eg : an HTML portion, not a full page).
hope that helps.
Water is not bad as long as it remains outside human body ;-)