Getting "Authorization code not issued to RP"

[Kulakshifd]

When I try to do a payment via sandbox I can log in to the buyer account but I'm getting an authorization error when redirecting to my application. The error is:

Got Http response code 401 when accessing https://api.sandbox.paypal.com/v1/oauth2/token. {"error":"invalid_authz_code","error_description":"Authorization code not issued to RP"

The clientID and secretKey are set properly. How can I fix this error? 

[ujobi_charlie]

I created a new client secret as a last ditch effort and that resolved the issue. It would really be helpful for Paypal to have a more actionable error message here.