problem to render <rich:column> with <a4j:poll>

[pangbuddy]

<h:form>
    <a4j:poll interval="2000" render="project-status" enabled="true"/>
</h:form>

<rich:dataTable id="project-list" value="#{projectBean.userProjects}" var="project">
    <rich:column id="project-status">
        <h:outputText value="#{project.progressCompletePercentage}%" />
    </rich:column>
</rich:dataTable>

Hello, My example code doesn't works, but if i simply replacing the poll's render value by dataTable's id "project-status" then it works completely. (I don't want to refresh the whole table in my case)

Richfaces version is 4.2.0 final.

PS: I had same usage in my other project with privious Richfaces version(3.3.3 final), it works well always.

please help, thanks advance!