Struts 2 newbie confused by value stack

[Rain Skat]

I am confused about how the value stack works. I thought every attribute in your action classes (with getter&setter methods) get pushed on the value stack automatically. Is this true or not? If it's true, how do you access the attributes of another action class? I've tried using stack.findValue method but it's returning empty. Here's code example:

public class FirstAction extends ActionSupport{
private Object a;
// getter and setter method for a
}

public class SecondAction extends ActionSupport{

public String execute() throws Exception {
ValueStack stack = ActionContext.getContext().getValueStack();
Object a = stack.findValue("a");
// At this point, Object a is null. Why???
}

[Manuel Schenkhuizen]

When you hit the action class, the value stack will push the property of your class on the value stack.