module VBA: add sub title ?

[pompaunpo]

in VBA template adv_portal i have:

<title>$vboptions[hometitle] <if condition="$pagetitle">- $pagetitle</if></title>

$pagetitle is the variable "title name" that I set in my module.

my module name is "book" and I see it as:

www.mysite.com/index.php?id_page=book&nr=22

my php module "book" executes a query to the database and shows the data es: book nr.22
In the page <TITLE> tag there is: "My site name - book"
"book" is $pagetitle, definite in the Admin CP module, OK?

how do I do to add in page module also the title of the book nr.22? es.
title book nr. 22 is "THE LAST HISTORY"

I would want the title of the page to be: "My site name - book - THE LAST HISTORY"

I could pass in GET variable es:

www.mysite.com/index.php?id_page=book&nr=22&subtitle=THE LAST HISTORY

how do I do to make to recognize the variable $subtitle?
in adv_portal i have add:

<title>$vboptions[hometitle] <if condition="$pagetitle">- $pagetitle</if>
<if condition="$subtitle">- $subtitle</if>
</title>

but doesn't work, I now see "My site name - book - " instead that "My site name - book"

in my php module I have add

$subtitle= $_GET['subtitle'];

but doesn't work

help me please

thanks