Pay Pal 10002 Security error - Security header is not valid

[stuffdone]

I can't troubleshoot your private USER/PWD/SIG details directly with you here. The error message is telling you they're wrong.
You'll need to log a ticket with Paypal support at www.paypal.com/mts

Thanks. I will inform the customer as I don't have the login for his paypal.

He set up the API this morning ( my time, 11PM his time ) then copied and pasted the details to me.

I won't hear from him again until tomorrow AM my time. Sucks working with someone on the other side of the world !