10002 API Set up error?

[scribblescrabble]

Alright, I've set up everything right regarding the installation of the store. The problem with PayPal has been there since I got the store up and running which was 11 days ago.

When I try to click the PayPal button I get the error listed below:
We are sorry for the inconvenience. The PayPal account authentication settings are not yet set up, or the API security information is incorrect. We are unable to complete your transaction. Please notify the store owner so they can correct this problem. (10002)

I'm using express obviously, I put in all the information that PayPal generated in their respected slots in the set up section. I copied and pasted everything accordingly. I can't seem to figure out the problem.

Have you guys ever experienced this? I'd like to know how to fix it! Thanks!

EDIT I tried both sandbox and live, regardless of the option I get the same error.