I am fetching rates & also creating easyship-shipments, but its only working properly with easyship mentioned category slugs

I am fetching rates & also creating easyship-shipments, but its only working properly with easyship mentioned category slugs. I am providing category title as regular life then its not working. But when I am providing easyship mentioned category slugs, then its working properly.

I am considering following link for such category slugs (but its for international shipping):

https://developers.easyship.com/docs/retrieve-product-categories

I am scripting from india for US addresses, may be because of that. Its working properly to category slugs.

If easyhip requests only working properly for category slugs, then please provide me such category slugs listing link.

Thanks in advance