Java EE (Java Enterprise Edition) General Discussion

hello, can some one tell what is the cause and the solution of the folowing exception :

EJB5070 Exception creating stateless session bean : [{0}]

com.sun.enterprise.InjectionException: Exception attempting to inject Env-Prop: ejb3.INplateformFacade/timerService@Field-Injectable Resource. Class name = ejb3.INplateformFacade Field name=timerService@java.lang.String@ejb3.INplateformFacade/timerService@@ into class ejb3.INplateformFacade
at com.sun.enterprise.util.InjectionManagerImpl._inject(InjectionManagerImpl.java:387)
at com.sun.enterprise.util.InjectionManagerImpl.inject(InjectionManagerImpl.java:206)
at com.sun.enterprise.util.InjectionManagerImpl.injectInstance(InjectionManagerImpl.java:127)
at com.sun.ejb.containers.StatelessSessionContainer.createStatelessEJB(StatelessSessionContainer.java:533)
at com.sun.ejb.containers.StatelessSessionContainer.access$100(StatelessSessionContainer.java:111)
at com.sun.ejb.containers.StatelessSessionContainer$SessionContextFactory.create(StatelessSessionContainer.java:772)
at com.sun.ejb.containers.util.pool.NonBlockingPool.getObject(NonBlockingPool.java:199)
at com.sun.ejb.containers.StatelessSessionContainer._getContext(StatelessSessionContainer.java:486)
at com.sun.ejb.containers.BaseContainer.getContext(BaseContainer.java:1675)
at com.sun.ejb.containers.BaseContainer.preInvoke(BaseContainer.java:1229)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:195)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandlerDelegate.invoke(EJBLocalObjectInvocationHandlerDelegate.java:127)
at $Proxy63.tachePlanifier(Unknown Source)

thanx on advance