Testing with Paypal Sandbox

[scinco]

I've been trying to test the whole account setup process and have added PayPal as the only 'Payment Gateway'.

 

I've setup an account for the PayPal Sandbox testing environment and have created a 'Test Account' (Seller) and have enabled the 'Test Mode' (which you are presented with when you are under the 'Test Account' page in the Sandbox.

 

Now I've entered the API username, password, and signature that was presented to me in the 'API Credentials' page and checked the 'Sandbox' checkbox on the WHMCS (version 4 btw) 'Payment Gateways' setup.

 

Thinking that was a piece of cake, I go into the /cart.php page, enter the required fields to create an account and then I am presented with the 'Check Out' button. So I click on that, enter the personal information, enter a fake credit card number (and after a bunch of failures I actually entered my real credit card information), and then I get a 'Credit card failed' error.

 

After reading some posts on this forum, I check out the Gateway logs.

 

There, I find this error repeated many times (due to my brute-force-approach on entering a credit card): L_LONGMESSAGE0 => This transaction cannot be processed due to an invalid merchant configuration.

 

Now knowing the jist of how I created the PayPal sandbox account and set it up in my WHMCS, what did I do wrong? Also, why am I presented with the credit card information on my site rather than having the user be redirected to PayPal? It's not a bad thing at all to accept the credit cards on my site, except the fact that all of the fake credit card numbers I used for testing were from the same fake cc generator I used to test another PayPal Sandbox account for work (only I had the 'Buy Now' button and it redirected to the sandbox Web site).

 

I tried finding answers on this forum, but either no one has addressed this issue on here or my search techniques suck. I'd appreciate any help anyone could offer. I am in no rush. I plan on going live with the site in about a month. So for anyone out there that has read all of this, thank you for being patient.

[scinco]

I see no one has experienced this issue?