I've set up a modalPanel in my web page, but every tme I open it, I'm getting a javascript error. 

<a4j:commandButton image="../images/about.png" id="aboutIcon" value="#">
    <rich:componentControl for="aboutModal" attachTo="aboutIcon" operation="show" event="onclick"/>                 
</a4j:commandButton>

<rich:modalPanel id="aboutModal">       
    <f:facet name="header">
        <h:outputText value="About NBC" />
    </f:facet>
    <f:facet name="controls">
        <h:panelGroup>
            <a4j:commandButton id="imgClose" image="/images/close.gif" style="border: none" />
            <rich:componentControl for="aboutModal" attachTo="imgClose" event="onclick" operation="hide" />    
        </h:panelGroup>
    </f:facet>
    <h:panelGrid columns="2" columnClasses="outputTextBoldRightAlign, outputText">

        <h:outputText value="Build Project: " />
        <h:outputText value="#{buildInfo.buildForgeProjectName}" />

        <h:outputText value="Build Release: " />
        <h:outputText value="#{buildInfo.buildForgeBuildRelease}" />

        <h:outputText value="Build Date: " />
        <h:outputText value="#{buildInfo.buildForgeBuildDate}" />

        <h:outputText value="Build Server: " />
        <h:outputText value="#{buildInfo.buildForgeBuildServer}" />

        <h:outputText value="Application Server: " />
        <h:outputText value="#{HostInfo.hostName}" />

    </h:panelGrid>
</rich:modalPanel>

The javascript error just says "Object Required" and points to line 2797, character 1. 

Any ideas?

Thanks