After many hours of searching on Paypal and nBill's forums, I still cannot find a solution.
When attempting to submit order to Paypal Sandbox, I receive the following error:The link you have used to enter the PayPal system is invalid. Please review the link and try again.
I currently have my the following settings for nBill:Payment Gateway (paypal)
IPN = index.php?option=com_netinvoice&action=gateway&task=ipn&gateway=paypal
Verify Callback = 1Order Form
Gateway - paypal
payment frequency code - ##5## (refers to field ID # - frequency)
When completing the order form, I am using the sandbox buyer email address. After submitting, it is directed to Paypal sandbox to enter buyer email and password. I enter the corresponding buyer email address and password, and receive the above error.
Any direction/advice on how to correct this.