Could you check the attachment in order to suggest me what to do?. Thanks in advance, Octavio.

This are the details of the logged notification:
Notification's details
Notification Id 	5
IP Address 	2601:2c6:8101:9ba0:d111:dcbe:2a9e:919e
Notification type 	Error returned by gateway (single payment) 	
Log date 	09/23/16 16:32:12 	
Username 	Laura Perez
Full name 	Laura Perez
User Id 	2149
Amounts and Currency
Currency 	USD 	
Amount: single 	7.99000 	
first 		
recurring 		
Tax 		
Shipping 		
Handling 		
Gateway fee 		
Exchange rate 		
Settle amount 		
Settle currency 		
Payment Method and Transaction details
Payment method 	- 	
Gateway account 		
Type 	web_accept 	
Transaction id (txn_id) 		
Parent Transaction id 		
Sale id (sale_id) 		
Auth id 	eac83e3d1b0e2 	
Payment date (as received) 		
Payment type 		
Payment status 	Denied 	
Pending reason 		
Reason code 	10002 	
Test payment notification 	0 	
Buyer details
First name 		
Last name 		
Company name 		
Address: Name 		
Address: Street 		
Address: City 		
Address: State 		
Address: Zipcode 		
Address: Country 		
Address: Country code 		
Address confirmation status 		
Payer name 	Laura Perez 	
Email 		
Payer id 	XXXX XXXX XXXX 9445 	
Payer status 	unverified 	
Country of residence 		
Contact phone of payer 		
VAT number of payer 		
Seller details
Business id of receiving account 		
Email of receiving account 		
Payment Receiver id 		
Sale's details
Invoice number 	N17 	
Memo from payer 		
Item number 	D17-2149-1 	
Payment basket 	15 	
Notification's raw data
Raw result 	FAILED
Raw data 	$response="TIMESTAMP=2016%2d09%2d23T16%3a32%3a13Z&CORRELATIONID=eac83e3d1b0e2&ACK=Failure&VERSION=97%2e0&BUILD= 000000&L_ERRORCODE0=10002&L_SHORTMESSAGE0=Security%20error&L_LONGMESSAGE0=Security%20header%20is%20n ot%20valid&L_SEVERITYCODE0=Error"
$results=array (
  'TIMESTAMP' => '2016-09-23T16:32:13Z',
  'CORRELATIONID' => 'eac83e3d1b0e2',
  'ACK' => 'Failure',
  'VERSION' => '97.0',
  'BUILD' => '000000',
  'L_ERRORCODE0' => '10002',
  'L_SHORTMESSAGE0' => 'Security error',
  'L_LONGMESSAGE0' => 'Security header is not valid',
  'L_SEVERITYCODE0' => 'Error',
);
$return=array (
  'level' => 'fatal',
  'errorText' => 'Security error. Please contact site administrator to check error log.',
  'errorCode' => '10002',
);
$request=array (
  'METHOD' => 'DoDirectPayment',
  'PAYMENTACTION' => 'Sale',
  'IPADDRESS' => '2601:2c6:8101:9',
  'CREDITCARDTYPE' => 'visa',
  'ACCT' => 'XXXX XXXX XXXX 9445',
  'EXPDATE' => '072017',
  'CVV2' => 'XXX',
  'EMAIL' => 'lpmassague@yahoo.es',
  'FIRSTNAME' => 'Laura',
  'LASTNAME' => 'Perez',
  'STREET' => '',
  'CITY' => '',
  'STATE' => '',
  'COUNTRYCODE' => NULL,
  'ZIP' => '',
  'AMT' => '7.99',
  'CURRENCYCODE' => 'USD',
  'DESC' => 'Membership for Laura Perez',
  'BUTTONSOURCE' => 'Joomlapolis_Cart_WPS',
  'CUSTOM' => '15',
  'INVNUM' => 'N17',
  'NOTIFYURL' => 'https://www.salesconsultantrating.com/index.php?option=com_comprofiler&view=pluginclass&plugin=cbpaidsubscriptions&cbpgacctno=6&cbpbasket=15&result=notify&cbpid=cbp57e55776726e4492453765&format=raw',
  'VERSION' => '97.0',
);
$_POST=array (
  'cbpnumber' => 'XXXX XXXX XXXX 9445',
  'cbpexpmonth' => '7',
  'cbpexpyear' => '2017',
  'cbpcvv' => 'XXX',
  'cbpfirstname' => 'Laura ',
  'cbplastname' => 'Perez',
  'cbPayNow' => 'pay',
  'cbpbasket' => '15',
  'cbpshopuser' => '14d673dbe24de125314d45c03938f160',
  'cbppaymenttype' => '1',
  'cbpcardtype' => 'visa',
);