Got "Exception starting filter PicketLink Security Filter: java.lang.NullPointerException" when deploy the project

According to the "Applying Security to a Forge Scaffold Project" section of the guide in http://forge.jboss.org/addon/org.picketlink.tools.forge:picketlink-forge-addon, I created a project and just wanna to deploy it on JBoss AS 7.1. After a lot of successful DB operation, I got exceptions as follows:

20:24:56,707 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[default-host].[/picketlink-forge-app]] (MSC service thread 1-4) Exception starting filter PicketLink Security Filter: java.lang.NullPointerException
at org.picketlink.http.internal.SecurityFilter.init(SecurityFilter.java:131) [picketlink-2.7.0.Beta1.jar:]
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:447) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3269) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.core.StandardContext.start(StandardContext.java:3865) [jbossweb-7.0.13.Final.jar:]
at org.jboss.as.web.deployment.WebDeploymentService.start(WebDeploymentService.java:90) [jboss-as-web-7.1.1.Final.jar:7.1.1.Final]
at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811)
at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1746)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_51]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_51]
at java.lang.Thread.run(Thread.java:744) [rt.jar:1.7.0_51]

20:24:56,711 ERROR [org.apache.catalina.core.StandardContext] (MSC service thread 1-4) Error filterStart
20:24:56,711 ERROR [org.apache.catalina.core.StandardContext] (MSC service thread 1-4) Context [/picketlink-forge-app] startup failed due to previous errors
20:24:56,716 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-4) MSC00001: Failed to start service jboss.web.deployment.default-host./picketlink-forge-app: org.jboss.msc.service.StartException in service jboss.web.deployment.default-host./picketlink-forge-app: JBAS018040: Failed to start context
at org.jboss.as.web.deployment.WebDeploymentService.start(WebDeploymentService.java:95)
at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811) [jboss-msc-1.0.2.GA.jar:1.0.2.GA]
at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1746) [jboss-msc-1.0.2.GA.jar:1.0.2.GA]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_51]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_51]
at java.lang.Thread.run(Thread.java:744) [rt.jar:1.7.0_51]

I haven't change any source codes of the forge-generated project but just change "jta-data-source" in the persistence.xml file.

Could anyone help to check the issue, please. Thanks a lot.