Error using Paypal Pro in Sandbox mode

-- url of the page with the problem -- : www.inkacollective.com/testing/consilium/
-- HikaShop version -- : 2.3
-- Joomla version -- : 3.3
-- PHP version -- : 5.x

I am using Paypal Pro payment method in sandbox mode. However, when I submit a credit card it does not let me do it and displays an

Error 10002: Security header is not valid

Is this just because I am in sandbox mode?

Hi,

developer.paypal.com/docs/classic/api/errorcodes/

There is no "10002" code with "security header". It is "10008".
"10002" is for authentication problems.

I will suggest you to contact the paypal support for more details.

Regards,

But as I fix, Any guide?

The best is to ask your PayPal support. They'll be able to review your account settings and tell you what is wrong.