Oauth 404 error on request_token and access_token calls


I am working through Twitter’s developer console and every time I make a /oauth/request_token.json call or /oauth/access_token.json call, I get HTTP/1.1 404 Not Found. I gave an oauth_callback url for the request token call and a valid oauth_verifier for the access token call. What seems to be causing the error?

Thank you!