I have everything going and fixed any issue that I had, but when I go to check out using paypal nothing happens.
when I click pay with paypal it does not leave or redirects me directly back to the check out page.
I have read most of the information on the web to resolve this issue but with no resolve.
2015-08-20T12:20:23+00:00 ERR (3):
exception 'Mage_Core_Exception' with message 'PayPal NVP gateway errors: Security header is not valid (#10002: Security error). Correlation ID: e3a986ee71b4d. Version: 72.0.' in /
I checked my API information directly from paypal copied and pasted without spaces.
As you mention, this is usually due to the API information being copied incorrectly.
Can you follow the below steps:
Also - ensure that you're fetching it from the correct place.. e.g using the Sandbox API button if you're using sandbox.