Gopu is your UserBean in the session Scope??? I think it is not.
The value is null when you change the selected value of the list or when you submit the form???
If it is null when you submit the form in the constructor of UserBean and your bean is on the request scope int the class of yur JSF Bean
public UserBean(){
HttpServletRequest req = (HttpServletRequest)FacesContext.getCurrentInstance().getExternalContext().getRequest();
String param = req.getParameter("visible");
if( param != null && "Yes".equals(param))
booleanValue = true;
else
booleanValue = false;
}
and in the jsp
<h:commandButton ......>
<f:param name="visible" value="#{UserBean.booleanValue}"/>
</h:commandButton>
This will do that the rendered property of your list be true and the value to be set in the bean and avoid it being null.
I hope you understand everything otherwise feel free to ask anything.