Found the issue. Your page has only
<html><head>
at the top, and to make the DHTML menu work with dropdowns, you need to specify the doctype and HTML version.
I took a copy of your test.php page, and just replaced the
<html><head>
with
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en-US">
<head>
and the drop-down menu works as expected
Your FrontPage isn't doing you any favors with writing HTML up-to-standards .. I suggest you find a different editor (especially since you're venturing into PHP, and FrontPage has a habit of munging PHP code).
Best regards,
Ken