Upgrade to RAM 7.2 meet Null Pointer Exception

My current project use the RAM 7.1.1.1 and deployed in the Websphere cluster, the WAS version is 6.1.0.27. Since our application need some RAM 7.2 feature, I begin to upgrade it to RAM 7.2.

I follow the following steps somebody send to me in the upgrade document:
First, I remove all the RAM applications originally deployed in Websphere cluster.
Then, I upload the version 7.2 com.ibm.ram.repository.setup.web.ear and deployClusterSetup.py into the server, and run the following command:
cd to WAS install dir/<profiles>/Dmgr01/bin
Ex: ./wsadmin.sh -lang jython -user <username> -password <pswd> -f /tempfs/iRAM7201/deployClusterSetup.py /tempfs/iRAM7201/com.ibm.ram.repository.setup.web.ear com.ibm.ram.repository.setup.web.ear

After that, I visit the RAM setup page :
http://xxx.ibm.com:9060/ram.setup/wizard/login.jsp
I want to use my RAM WAS admin user name and password to login. But after I login, it will report Null pointer exception:
java.lang.NullPointerException
at com.ibm.ram.repository.setup.web.WASServer.getInstallPrerequisiteStatus(WASServer.java:2127)
at com.ibm.ram.repository.setup.web.access.RAMConfigurationBean.getInstallPrerequisiteStatus(RAMConfigurationBean.java:750)
at com.ibm.ram.repository.setup.web.access.RAMConfigurationBean.getSettingsSelectionStatus(RAMConfigurationBean.java:710)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:79)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:618)
at org.apache.commons.el.ArraySuffix.evaluate(ArraySuffix.java:314)
at org.apache.commons.el.ComplexValue.evaluate(ComplexValue.java:145)
at org.apache.commons.el.ExpressionEvaluatorImpl.evaluate(ExpressionEvaluatorImpl.java:263)
at org.apache.commons.el.ExpressionEvaluatorImpl.evaluate(ExpressionEvaluatorImpl.java:190)
at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:754)
at com.ibm._jsp._index._jspx_meth_c_set_14(_index.java:902)
at com.ibm._jsp._index._jspService(_index.java:492)
at com.ibm.ws.jsp.runtime.HttpJspBase.service(HttpJspBase.java:87)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1152)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1087)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:145)
at com.ibm.ram.repository.setup.web.wizard.servlets.main.SetupAssistantFilter.doFilter(SetupAssistantFilter.java:66)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java:87)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:837)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:680)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:588)
at com.ibm.ws.wswebcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:524)
at com.ibm.wsspi.webcontainer.servlet.GenericServletWrapper.handleRequest(GenericServletWrapper.java:122)
at com.ibm.ws.jsp.webcontainerext.AbstractJSPExtensionServletWrapper.handleRequest(AbstractJSPExtensionServletWrapper.java:232)
at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:3548)
at com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:269)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:818)
at com.ibm.ws.wswebcontainer.WebContainer.handleRequest(WebContainer.java:1478)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:125)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:458)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:387)
at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:102)
at com.ibm.ws.ssl.channel.impl.SSLReadServiceContext$SSLReadCompletedCallback.complete(SSLReadServiceContext.java:1818)
at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:136)
at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:196)
at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:751)
at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:881)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1497)

Is anybody can help to check this problem? Thank you.