unauthorised payment

[sassi_nabhani]

i need help future payment work in sandbox when i try live mode this is error

URL: https://api.paypal.com/v1/payments/payment } { status code: 401, headers

"debug_id" = 5ba196222d74f;

    "information_link" = "https://developer.paypal.com/docs/api/payments/#errors";

    message = "Unauthorized payment.";

    name = "UNAUTHORIZED_PAYMENT";