Not encoding the OAuth signature...?

[ghost]

I've noticed, using Postman, that I manage to authenticate and get tokens, if I unchek "Encode Oauth Signature", while using this in my code, does not work and I get 403: Invalid signature. Expected signature base string...

(format "%s" (cdr (assoc "Authorization" (oauth-request-to-header (oauth-sign-request-hmac-sha1 (oauth-make-request "https://www.instapaper.com/api/1.1/oauth/access_token" "907c713f7d564099b3sdwdcee2b20126") "7a9dd1867ert4be59ff0e53968206196")))))

The same message appears in Postman, if I do check "Encode OAuth signature"