hello,I find a problem trouble me a lot about No VaadinSession bound to cur

follows is the detail of the exception:

BeanCreationException: Error creating bean with name 'EmergencyplanObject': Scope 'vaadin-session' is not active for the current thread; 
consider defining a scoped proxy for this bean if you intend to refer to it from a singleton; nested exception is java.lang.IllegalStateException: No VaadinSession bound to current thread
Caused by: java.lang.IllegalStateException: No VaadinSession bound to current thread

I’m confuse what that means ,so please tell me why I can’t create a new bean by reflect with @vaadinSessionScope?
thanks for help.

and next is my code:

ApplicationContext applicationContext = ApplicationContextRegister.getApplicationContext();
Object bean = applicationContext.getBean(className);