In the Cybersource Server Release Notes for February 27, 2013, Security Keys are now separate for the Test and Live environments.
It is possible that the user is still using the live Security Key File and not a Test Security File on their Sandbox Account.
If that is the case, user needs to download Test Security Key File using their Test Business Center.
To generate transaction Security Key (Simple Order API) for CyberSource Credit Card Processing setup, perform the following:
1. Log in to the Test Business Center at https://ebctest.cybersource.com/ebctest/login/Login.do
2. Click Account Management.
3. Click Transaction Security Keys.
4. Click on Security Keys for the Simple Order API link.
5. Click Generate Key. A warning message appears.
6. To accept the security warning, click Yes.The download may take several minutes during which the applet may appear as a large gray box. Another warning message appears.
7. Verify that the certificate is signed by CyberSource Corporation, and click Yes. Another warning message appears.
8. To accept the certificate, click Yes or Always.The New Security Key window appears. When the Generate Certificate Request button appears, the download is complete.
9. Click Generate Certificate Request. Messages appear in the Messages box while a new key is generated. Another warning message appears.
10. To accept the certificate, click Yes or Always.Messages continue to appear in the box. Your browser opens its Save As dialog box.
11. Choose a safe location for your key (.p12).
12. To verify that your key is active, click Transaction Security Keys in the navigation pane. Your new key is listed at the bottom of the table. You have finished generating your key.
Upload the new Test Security Key File to NetSuite after. Please navigate to Setup > Accounting > Credit Card Processing > Edit CyberSource Account.
You may want to open the following link for further information: