How to send a hidden field with Ajax in Struts 2?

Here is my code:

<s:form
     id="deployChapters%{#chapterTree.nodeId}" 
     action="%{deployChapterUrl}"
     theme="simple"
     method="POST">
     <s:hidden name="nodeId" value"%{#chapterTree.nodeId}" />
</s:form>

I submit this form with Ajax. With Firefox, the hidden field nodeId is not sent. It is with Chrome or IE.

How can I ask FF to send the hidden field?

Finally, here is the solution I came up with:

• I detect when the form is submitted and I programmatically add the hidden field to the form.