javax.servlet.ServletException: Cannot find ActionMappings or ActionFormBeans collection

 package  app;
 import  org.apache.struts.action.*;
 public   class  RegisterForm  extends  ActionForm {
 protected  String username;
 protected  String password1;
 protected  String password2;
 public  String getUsername () { return   this .username;};
 public  String getPassword1() { return   this .password1;};
 public  String getPassword2() { return   this .password2;};
 public   void  setUsername (String username) { this .username = username;};
 public   void  setPassword1(String password) { this .password1 = password;};
 public   void  setPassword2(String password) { this .password2 = password;};
}

 package  app;
 import  org.apache.struts.action.*;
 import  javax.servlet.http.*;
 import  java.io.*;
 public   class  RegisterAction  extends  Action {
 public  ActionForward perform (ActionMapping mapping,
ActionForm form,
HttpServletRequest req,
HttpServletResponse res) {
// b Cast the form to the RegisterForm
RegisterForm rf = (RegisterForm) form;
String username = rf.getUsername();
String password1 = rf.getPassword1();
String password2 = rf.getPassword2();
// c Apply business logic
 if  (password1.equals(password2)) {
 try  {
// d Return ActionForward for success
UserDirectory.getInstance().setUser(username,password1);
 return  mapping.findForward("success");
}  catch  (UserDirectoryException e) {
 return  mapping.findForward("failure");
}
}
// E Return ActionForward for failure
 return  mapping.findForward("failure");
}
}

<?xml version="1.0" encoding="ISO-8859-1" ?>
<!DOCTYPE struts-config  PUBLIC 
"-//Apache Software Foundation//DTD Struts Configuration 1.0//EN"
"http://jakarta.apache.org/struts/dtds/struts-config_1_0.dtd">
<struts-config>
<form-beans>
<form-bean name="registerForm" type="app.RegisterForm"/>
</form-beans>
<action-mappings>
<action path="/register"
type="app.RegisterAction"
name="registerForm">
<forward name="success" path="/success.html"/>
<forward name="failure" path="/failure.html"/>
</action>
</action-mappings>
</struts-config>