facebook problem about opening a dialog box

Question

I have a problem regarding opening a new dialog box. Which encounter an error like "MOCK AJAX ERROR:".

I have writtten below code for dialog box:

<fb:dialog id="my_dialog" cancel_button=1>
    <fb:dialog-title>My Little Dialog</fb:dialog-title>
    <fb:dialog-content>Do you like my little dialog?
        <form id="my_form"> <p/>
            <input type="radio" name="like_dialog" value="yes"/>Yes <br/>
            <input type="radio" name="like_dialog" value="no"/>No <p/>
            <input type="hidden" name="arc" value="1"/>
        </form>
    </fb:dialog-content>
    <fb:dialog-button type="submit" value="Yes" form_id="my_form" />
</fb:dialog>
Would you like to see a <a href="#" clicktoshowdialog="my_dialog">dialog?</a>