Contact 7 Paypal Sandbox

I have added my live account ID and sandbox business email to the Paypal account settings. I used the personal sandbox email and password to log into PayPal from my websites product, but I keep getting “Some of your info didn’t match. Try again, change the email address, or get help if you forgot your password.” error. There is not a CSC code nor an address in the sandbox user account to use the fake credit card as an option. Any help setting up my sandbox to text out my Paypal for my products on my website will be much appreciated.