When validating a messagefrom response page, it fails

We get a nullPointer exception in the logs, and a message "transaction fail" in the gui
http://sake.irisa.fr/XDStarClient/messages/allRespondingMessages.seam

Caused by: java.lang.NullPointerException
at net.ihe.gazelle.xdstar.common.action.RespondingMessageManager.validateReceivedMessage(RespondingMessageManager.java:236) [XDStarCommon-ejb.jar:1.0.13-SNAPSHOT]
at net.ihe.gazelle.xdstar.common.action.RespondingMessageManager.validateReceivedMessage(RespondingMessageManager.java:48) [XDStarCommon-ejb.jar:1.0.13-SNAPSHOT]
at net.ihe.gazelle.xdstar.common.action.MessageManager.validate(MessageManager.java:348) [XDStarCommon-ejb.jar:1.0.13-SNAPSHOT]
at net.ihe.gazelle.xdstar.common.action.MessageManager.selectAndValidate(MessageManager.java:292) [XDStarCommon-ejb.jar:1.0.13-SNAPSHOT]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_151]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) [rt.jar:1.7.0_151]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_151]
at java.lang.reflect.Method.invoke(Method.java:606) [rt.jar:1.7.0_151]
at org.jboss.seam.util.Reflections.invoke(Reflections.java:22) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at org.jboss.seam.intercept.RootInvocationContext.proceed(RootInvocationContext.java:32) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:56) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at org.jboss.seam.transaction.RollbackInterceptor.aroundInvoke(RollbackInterceptor.java:28) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at org.jboss.seam.core.MethodContextInterceptor.aroundInvoke(MethodContextInterceptor.java:44) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at org.jboss.seam.core.SynchronizationInterceptor.aroundInvoke(SynchronizationInterceptor.java:35) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at org.jboss.seam.intercept.RootInterceptor.invoke(RootInterceptor.java:107) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at org.jboss.seam.intercept.JavaBeanInterceptor.interceptInvocation(JavaBeanInterceptor.java:196) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at org.jboss.seam.intercept.JavaBeanInterceptor.invoke(JavaBeanInterceptor.java:114) [jboss-seam-2.3.1.Final.jar:2.3.1.Final]
at net.ihe.gazelle.xdstar.common.action.RespondingMessageManager_$$_javassist_seam_45.selectAndValidate(RespondingMessageManager_$$_javassist_seam_45.java) [XDStarCommon-ejb.jar:1.0.13-SNAPSHOT]