Grape api with devise token auth

I am using grape gem, devise_token_auth, grape_devise_token_auth and i'm able to sign up and sign in, it is returning access token in the header

access-token →ssssssssssssss
client →sssssssssssssss
expiry →1480743645
token-type →Bearer
uid →sssssssssss@gmail.com

But if i access a url with these details in the header of the next url, the url still shows 401 unauthorized, how do i authenticate these url for ex /api/v1/list_users