Hey Constant Contact!
I am having a problem in which I believe I created. I authenticated a user with my API key and had a custom sign up form. It was all working and no authentication issues until I accidently logged in with that same users account for another feature I was creating with the API. So basically I had the same user name using the same API key and consumer secret twice. BTW, I am using Oauth and your constant contact libraries. I hope you are following me here. This is a funky situation.
I have fixed the problem and removed the other authentication I had stored, but I am still getting the authenticaion fail. I have no clue if it is becuase I some how locked that user out by have two authentications for the same user. I need some help here. I have also re-authenticated with success and created a new access_token, but still it is not working.
Are you using OAuth 1.0a or 2.0? Also, can you PM me the username of your customer (not password), API key you're using and the Authentication token that is giving the 401 Unauthorized? I have the ability of looking into your current authentication data directly in the database to see exactly what is going on with Authentication tokens with that information.
Errrr..After looking through the library (CTCT_PHP_Library). I believe it is using Oauth1.0. I don't see anywhere where it says 1.0a. Sorry if this caused any confusion on your end.
Dave forwarded the information you provided to me, and I've opened a ticket and sent an email through our support systems. I'll be happy to offer troubleshooting assistance.