BI Publisher 11g - Failed Secure Java Extensions check when use BIPEXT library

Hi,
I have a error when I try run BIP report with below namespace in rtf template:
<?namespace:bipext=http://www.oracle.com/XSL/Transform/java/oracle.com.xmlpublisher.reports.BIPExtension?&gt;

I need this lib to convert timestamp field to string format in a template.

Have you any idea ?

Thanks,
Marcin

Below logs with error:


[2013-07-17T04:19:08.901-05:00] [bi_server1] [ERROR] [] [oracle.xdo] [tid: 36] [userId: <anonymous>] [ecid: 87ae3bc04a436494:1facf7ff:13fae83e488:-8000-0000000000072d16,0] [APP: bipublisher#11.1.1] Namespace 'http://www.oracle.com/XSL/Transform/java/oracle.com.xmlpublisher.reports.BIPExtension' failed Secure Java Extensions check.