While i am trying to payment through paypal using dodirect payment api,its gives me following response :
[TIMESTAMP] => 2018-01-17T10:31:55Z
[CORRELATIONID] => cc202be065d4f
[ACK] => Failure
[VERSION] => 57.0
[BUILD] => 39206242
[L_ERRORCODE0] => 10002
[L_SHORTMESSAGE0] => Security error
[L_LONGMESSAGE0] => Security header is not valid
[L_SEVERITYCODE0] => Error
I am using Live credentials and its working fine in sandbox account.
Please make sure you correctly enter the API user name, API password and API signature of your Live PayPal account instead of your Sandbox PayPal account.
In addition, when you copy and paste API credentials, please make sure that there is no blank spaces before or after where you have highlighted to copy the text. You can firstly paste the information into a text editing program such as Notepad or TextEdit to ensure that there are no extra spaces.
Furthermore, please also double check that you have not wrongly set the Endpoint to Sandbox mode as follows. Instead, "sandbox" should be removed and the Endpoint of PayPal Live site is 'https://api-3t.paypal.com/nvp' without "sandbox"
'api_endpoint' => 'https://api-3t.sandbox.paypal.com/nvp',
'api_username' => 'example_api1.email.com',
'api_password' => 'your_password',
'api_signature' => 'your_signature',