Multivaluefield - on-value-changed event fires only once

Hi.
I have form with multivaluefield widget. Definition is as follows:

<fd:multivaluefield id="questionsLectures">
            <fd:label>Lectures: </fd:label>
            <fd:datatype base="string"/>

            <fd:selection-list type="flow-jxpath" list-path="lectures" 
value-path="value" label-path="label"/>

            <fd:on-value-changed>
                <javascript>
                    var form = event.source.form;

                    var console = 
cocoon.createObject(Packages.pl.com.piechowicz.PeoxProject.ConsoleUtil);
                     console.println('Value changed in questions');

                </javascript>

            </fd:on-value-changed>

        </fd:multivaluefield>

I`m using "double-listbox" styling and I would like to handle 
value-change event, but when I move an item between lists event handler 
fires only first time. I see no errors in jetty console or js console in 
browser. When I changed styling to "checkbox" value-change event doesn`t 
fire.

Any ideas ?

Regards,
Tomek Piechowicz