The code for the view cart button relies on the including of the WA_eCart/<your cart name>_PHP.php file. That include line of code would normally look like this:
<?php
//WA eCart Include
require_once("WA_eCart/eCart1_PHP.php");
?>
If you have the template in a template directory you might need to add ../ to the front of this path like this:
<?php
//WA eCart Include
require_once("../WA_eCart/eCart1_PHP.php");
?>