Error: Security header is not valid on Paypal checkout

[Dihusky]

Hi,

 

The error displays on the confirmation page when checking out. If I click the paypal button nothing happens.

 

Have I missed something!!

 

I have installed version 2.2 RC2 and removed all payment options except Paypal Express. I have an API and my set for the Sandbox server, Transaction method is Sale and Zone is Australian zones. This was not installed by me as an add-on but as part of the original download.

 

http://scubaservice.com.au/shop/

 

Thanks