Paypal Direct test environment

We got our site up and running using nopCommerce 3.50.  We now want to use Paypal Direct for our credit card processing.  But we would like to test this first.  I already installed the Paypal Direct plugin.  I also signed up for a free Paypal business account.  I added all the API username, password, and signature to Paypal in nopCommerce.  I also checked the Sandbox check box.  

Paypal provided me a sandbox buyer that I can use for testing.  This includes a test credit card.

So I login to my nopCommerce site as this test buyer.  I order some product and go to checkout.  I enter the test credit card and click Confirm.  I then get this error:

Payment error: LongMessage: Security header is not valid ShortMessage: Security error ErrorCode: 10002

So what am I doing wrong?

I just went through setting up our PayPal Direct plugin.  For it to work you have to have PayPal Payments Pro activated which costs $30/mo.  You can also upgrade your sandbox account to pro as well for testing (I did this after upgrading to PayPal Advanced, at which point sandbox worked for me for plugin but live did not, not sure if the option to upgrade sandbox is there with just a live account).

Here is my recent thread on the issue:
https://www.nopcommerce.com/boards/t/35646/paypal-advanced-or-paypal-payments-pro-required-for-paypaldirect-plugin.aspx

Let me know if you have any other questions or problems.

Alec,

Thanks for the response.  Yeah, I think you are right.  I found out we already have the $30 a month account but I set-up a new free one and discovered this won't work.  Paypal is going to give us a test buyer account that I can test with.  So I should be ok now.

Bob