I have a working OAuth process for authorizing with Google. My app can get data from the Google Sites API from areas that only the account used to authorize it has access, so I know that much is working. The trouble is creating new data via the API. I consistently get "Unknown authorization header" when trying to POST to the endpoint. The real frustration appears when I try to use the Google Oauth Playground. I put in the credentials I have, put in the same endpoint and same request body, and try it there -- and everything works perfectly.
I'm using Ruby 1.9.3 on the API side, and I've tried with both oauth-ruby and the Google-written signet client. Both do the same thing. I've verified and re-verified that the credentials are as I expect them to be (both just checking, and using the same ones in the Oauth Playground and seeing them work).
I have no idea why this is happening, because there's precious little information coming from Google's API about what's actually wrong with my request.
For the record, I'm using; Ruby 1.9.3 oauth-ruby and signet for clients OAuth 1.0 HMAC-SHA1 hashing 3-legged authorization