Problems in Sandbox and Production

Hi, Recently the company I work for requested to create an account with ExactPay, I am coding your APIs in my Backend, but I have problems both in Sandbox and in Production.

In Sandbox I cannot authenticate or create payments with the APIs. Error 404 not found.

In Production I can Authenticate but when creating a payment with https://api.exactpay.com/payments the response is "Invalid API Key supplied", but the fact is that I have placed all the Keys given by you in my dashboard and none works. I need help.