problem with binding a input

Hi!
I'm very new in spring and webflow, and i have some troubles for understand a few things.

I have a form and when i click on a <a> (the call is ok) it doesn't bind my form.
Some code:

flow.xml

Code:

---

    <var name="model" class="org.fidesol.bestmark.flowController.IndicatorController" />
    <view-state id="form" view="editarIndicadoresEntidad/form" model="model"  >
        <transition on="add">
            <evaluate expression=" model.addValue(messageContext)" />
        </transition>
    </view-state>

---

indicatorController

Code:

---

public class IndicatorController implements Serializable {
    String value;
    String note;
    private static final long serialVersionUID = 12L;

  /*GETTERS AND SETTERS*/
........
 public boolean addValue(MessageContext messages){
......
}

---

jspx

Code:

---

        <form method="POST" >
<input type="text" name="note" value="${model.note}" id="note"/>
<input type="text" name="value" value="${model.value}" id="value"/>

 <a class="btn" href="${flowExecutionUrl}&amp;_eventId=add"> i</a>

</form>

---

The form is seen ok, but when i change the values, those doesn't bind

Any idea of my problem?
I proved also with <form:form> but i don't know how to use modelAtribute option
Any help would be apreciatted.

Thanks!