Why jsp can't get the Vector fill with user-defined class by the Remote interface?

Because It is a big project so i provide a model to express my
question,
Qestion is:I want get the Vector full fill with the a Object in Jsp.
but I can't get it,There will problem will return test return,but we I
Choose String but no class a 's object ,It can be return successful.It
seems that jsp Can't recognize the class a,,but I really include the
Ejb module in jsp's lib.and editor alse prompt a's information.
I alse test it in JBoss server It alse occur Exception!
I cant understand why,
so come to here ask why?Please help me,3ks very much!!!

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I use Netbean 6.1,Glassfish.Ejb3
import javax.ejb.Stateless;

1.
@Stateless(mappedName="T")
public class vectorBean implements vectorRemote {
//Vector v;
//@PostConstruct
//public void Init(){v=new Vector}

    public Vector test(){
        Vector v=new Vector();
        v.add(new a("alex",14));
        return v; }
 }

2. a is a simple class
public class a {
    public String m;
    public int n;

    public a(String m, int n) {
        this.m = m;
        this.n = n;
    }
  getter,and setters!
}

3.Jsp
     InitialContext ctx=new InitialContext();
     //ShoppingCartRemote
s=(ShoppingCartRemote)ctx.lookup("shopcart");
     vectorRemote s=(vectorRemote)ctx.lookup("T");
     Vector v=s.test();
    Enumeration e=v.elements();
    while(e.hasMoreElements()){
        a p=(a)e.nextElement();
        out.println(p.m);
    }