Java EE (Java Enterprise Edition) General Discussion

I've encountered a problem while developing a forum using JSF. See this code:

<h:form id="commmentForm" formName="commentForm" >
<h:input_hidden id="pageId" valueRef="CommentBean.pageId" value="${article.id}"/>
<h:input_text id="userName" valueRef="CommentBean.userName"/>
<h:input_text id="userEmail" valueRef="CommentBean.userEmail"/>
<h:input_text id="userURL" valueRef="CommentBean.userURL"/>
<h:input_textarea id="content" valueRef="CommentBean.content"/>
<h:command_button id="submit" label="Leave A Comment" commandName="submit" actionRef="CommentBean.createAction" />
</h:form>

I was trying to specify a hidden field that represents the unique ID number of the current article using <h:input_hidden> tag above. But RI complains that runtime expression is not permitted in 'value' attribute. So I set the attribute 'value' to arbitrary number such as '2', but it seems that CommentBean.pageId is still null.

So the question is:

1. Why can't I use EL in JSF tags attributes?

2. How can I resolve my problem mentioned above?

Thanks very much in advance!