404 error when accessing ?wc-api=WC_Gateway_PayPal

Hello there,
Please check this document about debugging IPN issues and let us know if you find out anything: https://docs.woocommerce.com/document/paypal-standard/#section-5

Thank you!

I already looked at that but all my setting are correct. Am I supposed get a 404 error when I go to https://mysite.com/?wc-api=WC_Gateway_PayPal?