primefaces - Issue with Dynamic Columns

Question

I am using primefaces 3.5 . I am trying to use <p:ajax> with dynamic columns.

<p:ajax> does not fire the action I expect. My code is given below

<p:datatable  id = "table">
    <p:columns id="columns" value="#{controller.columnHeaders}" var="columnHeader" >
        <f:facet name="header"> 
            <h:outputText  value="#{columnHeader._label}" />
        </f:facet>
    <p:inputText rendered="#{columnHeader._editable}"
                 value="#{orderController.columnValue}" >
        <p:ajax event = "keyup" update = "table"
                listener = "#{controller.totalRateCalculation}"/>
        </p:inputText>
    <h:outputLabel rendered="#{!columnHeader._editable}"
                   value="#{orderController.columnValue}" />
    </p:columns>
</p:datatable>

Anybody help me !!!