I'm getting the following error during checkout and was wondering if anyone knows how to go about fixing this.
I only have Paypal Express (on aspdotnetstorefront version. 10.0.2)
"Error:  Security header is not valid"
I logged in to my paypal and supplied the correct values for api password, login / key etc..
Also, i'm not using any other gateway. It's already configured for SSL.
Currently it's in test mode. Was wondering if there is some special sandbox configuration i need. The document didn't have any info on sandbox testing configs etc..
Please let me know.