paypal direct 10501 error message

Hi

I've checked the forums and the only help I've seen is:
Click yes to billing agreement: done
Have website site pro set up: done
use sandbox api with sandbox enabled: done

Notes: Paypal express sandbox test worked; ssl cert working fine

Help please!

Hi Steve,

I have similar issue.
Can you please help me out

https://www.x.com/people/binu/blog/2010/02/10/struck-of-error-code-10501-this-transaction-cannot-be-processed-due-to-an-invalid-merchant-configuration