[Lynne]

This line here is registering a variable named $php_include:

PHP Code:

vB_Template::preRegister('footer',array('php_include' => $php_include)); 


That line would allow you to use this line in the footer template:

{vb:raw php_include}

If you want to use the variable $userboxinsert, then you need to preregister that variable, not php_include.

PHP Code:

vB_Template::preRegister('footer',array('userboxinsert' => $userboxinsert));