Security header is not valid my presthashop

[manojb05]

Hi,

My Sandbox test account configure with presthashop i got a error. please let me know, something i doing wrong.

  Error occurred:

Please try to contact the merchant:

1. <b>PayPal response:</b>
2. TIMESTAMP -> 2016-01-17T13:22:37Z
3. L_ERRORCODE0 -> 10002
4. L_SHORTMESSAGE0 -> Security error
5. L_LONGMESSAGE0 -> Security header is not valid
6. L_SEVERITYCODE0 -> Error