Using DWCC 2014.1 and latest eCart v6 with complete site
The site is only on my PC using localhost at this time. I wanted to resolve this issue before going live.
The eCart Gateway Credentials are as follows:
Debug Mode: yes
Gateway: PayPal
Service: PayPal API
Use Test Mode (sandbox): yes
Username, Password and Signature: From my PayPal commercial API credentials
Perhaps this will help