jsf - h:inputText が a4j:commandLink で機能しない

Question

myBeanrequest範囲内です。

<h:form id="indexFormID">
<a4j:outputPanel ajaxRendered="true" layout="block">
    <h:inputText id="inputForHD" value="#{myBean.inputParam}"></h:inputText>
    <a4j:commandLink value="Submit" action="#{myBean.myMethod}" reRender="renderSuccess" process="indexFormID:inputForHD"></a4j:commandLink>
</a4j:outputPanel>


 <h:panelGroup id="renderSuccess">
    <h:panelGroup rendered="#{myBean.someBoolean}">
       //Some other JSF components go here          
    </h:panelGroup>
 </h:panelGroup>
</h:form>

MyBeanクラス定義:

private String inputParam;
//Getters and setters are there

public String myMethod()
{
    log.debug("~ Value of inputParam" +this.getInputParam()); //This is printing null value for inputParam 
    //when commandLink is clicked
    return null;
}

inputParam入力パラメータが設定されないのはなぜですか?