API oauth error

I am trying to connect to OAuth with Embarcadero REST components but get an error.
Do you have to do something to activate the API and OAuth more than register the application?

The error response:

OAuth Verification Failed: 
Verification of signature failed (signature base string was "POST&http%3A%2F%2Finfoscreen%2Fservices.php&method%3Drequest_token%26oauth_consumer_key%3Dc6e45ae48694f74f8eaacf281b4d73fb055854689%26oauth_nonce%3D811832ea2eb54037b83fe06428ffcb5e%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D1434970272%26oauth_version%3D1.0%26service%3Doauth"). with  Array
    [0] => b87c36305387d0af6ac5690f496c8600
    [1] => 
    [2] => 

Sorry for the delay - there isn’t anything else you need to do after registration. The error seems to indicate that the oAuth client is sending an incorrect signature. What system are you using to send the request?