PayPal Pro Integration: Security header is not valid error in the Form

Hello. I know that I have correctly entered my API credentials a dozen times over directly from PayPal Pro. I'm not in Sandbox mode. I still can't make my payment form go live. What else am I missing? I keep getting the same error message when attempting to checkout. I'm not sure if I have a cart already built into my app or not. It's all so confusing, and it looked straightforward at first. I have done all of the steps as listed on the form. I need to walk through this process with a live agent. Is there a number I can call? Please, please help.

Could you please re-generate your PayPal API keys and configure the newly created API? Are you having a PayPal business account?

Guide: https://www.jotform.com/help/183-Difference-Between-PayPal-and-PayPal-Pro

Guide: https://www.jotform.com/help/284-How-to-Obtain-PayPal-API-Credentials

On the creation of new credentials if you are still unable to submit the Form then please try deleting the integration and then connecting it once again. The configured products would be retained.

Let us know how this goes.

Thanks.