Struts Application in RAD error

I am trying to run the Struts Application in RAD using Websphere application 6.1 but its not working its giving as error:

There is no Action mapped for namespace / and action name . - [unknown location]
at com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:178)
at org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:61)
at org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:39)
at com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:47)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:478)
at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:395)