Php sessions not working

Hi Guys,

I’m trying to set a session variable that changes the BG style of a page.
And the php is just totally not working, Any help would be greatly appreciated.
Here is the code.

**HEADER
**<style> <?php
session_start();

if(isset($SESSION[‘bg’]))
echo "body{
background-image: url(img/bg
" . $_SESSION[‘bg’]; . “.jpg);
}”

else
print “body{
background-image: url(img/bg_1.jpg);
}”

?>
</style>

**HLINKS
**<a href="#<?=$_SESSION[‘bg’]=‘1’; ?>">1</a>
<a href="#<?=$_SESSION[‘bg’]=‘2’; ?>">2</a>
<a href="#<?=$_SESSION[‘bg’]=‘3’; ?>">3</a>

Thanks.