Paypal Express error 10002 using Sandbox

I'm receiving the following error when trying to use Paypal Expres:

We are sorry for the inconvenience. The PayPal account in this store is presently misconfigured to use mixed sandbox and live settings. We are unable to complete your transaction. Please notify the store owner so they can correct this problem. (10002)

Payment Zone
--none--
Set Order Status
Processing [2]

Set Unpaid Order Status
Pending [1]

Set Refund Order Status
Pending [1]

Express Checkout: Require Confirmed Address
No

Express Checkout: Select Cheapest Shipping Automatically
Yes

Express Checkout: Skip Payment Page
Yes

Express Checkout: Automatic Account Creation
Yes

Payment Action
Final Sale

Transaction Currency
Selected Currency

PayPal Page Style
Primary
Live or Sandbox
sandbox

Debug Mode
Off

Any Ideas/help appreciated

You have selected "sandbox" for your server choice, but you need to get new API Credentials from your sandbox account and use them in the module in place of your live credentials.

The sandbox authentication system is completely separate from the live system. Hence the need to get new credentials to use the sandbox.

Thanks Chris,

I must have missed the distinction when I got the APIs.

I'll go back and chek it out.

Incorrect Paypal username, password or key values will also result in this error. Double check those values in ZenCart if you are getting this message.

Yes. Go to your Profile in Paypal. Your API username and password are different thany our Paypal username and password. I just spent more than a few minutes beofre this forum saved me the frustration.

I am brand new to Zen Cart & I am having a similar problem.

When I click on express check-out on my site it goes to a new page that says:

Warning: array_merge() [function.array-merge]: Argument #1 is not an array in /home/manderhe/public_html/includes/modules/payment/paypalwpp.php on line 1467

Warning: array_merge() [function.array-merge]: Argument #2 is not an array in /home/manderhe/public_html/includes/modules/payment/paypalwpp.php on line 1467

Warning: Cannot modify header information - headers already sent by (output started at /home/manderhe/public_html/includes/modules/payment/paypalwpp.php:1467) in /home/manderhe/public_html/includes/functions/functions_general.php on line 44

Do I need to get new API credentials from my Sandbox acct as well? If so, How do I do this?

Thanks so much!!!

You just need to install the latest Patch for PayPal on v1.3.7:
http://www.zen-cart.com/forum/showthread.php?t=56216

This will sound real dumb, but once I download the fix were do I put it on my cart?

The file structure of the fix matches the file structure of your site to overwrite the files ...
http://www.zen-cart.com/forum/showthread.php?p=365905#post365905