How to get SEO URL from Add On?

I am working on an add-on for version 2.2.4 and trying to get the SEO URL of products.

I am using this code: fn_url(“products.view?product_id=53”, 'C', 'http', '&', $lang_code);

but it returns product-53.html when it should return seo-name.html.

Can anyone advise what I'm doing wrong?

It would appear there's no seo name set for product_id 53.

Product ID 53 did have an SEO name however… I was not sending the language variable correctly $lang_code was not a valid variable. I changed it to [color=#000000][size=2]CART_LANGUAGE and now it works. :)[/size][/color]