permalinks

I have to rewrite the product’s permalink by changing it from the default /product/product-name into /%product-cat%/product-name. %product-cat% is a custom category. But after I rewrite it, the pagination for product review is not working. Not matter what page I click, the url is correct but the reviews are always stuck at first page. This is my first attempt on doing a permalink rewrite. Did I missed out anything or added wrong line of code thus causing the pagination query to fail?

Inside my index.php, I have a new WP_Query() for a custom post type that I have named “todo”.