Unauthorised Access

[manibha-jain]

Hi i am trying to access user's seller account data using web authorisation.
Till amazon send user back to my website and i use https://api.amazon.com/auth/o2/token api to generate refresh token everything works fine.
But when i use this refresh token in my API it doesn't work.

Catalog(credentials=credentials,marketplace=Marketplaces.US).list_categories()

It is giving me the following error.

{'message': 'Access to requested resource is denied.', 'code': 'Unauthorized', 'details': ''}

I read about RDT but it says catalog api doesn't require RDT token.

Am i missing something here?.