JSObject returns null

Question

I have a JSF page with two applets, both applets communicate with JSF by javascript, each applet communicate with external devices and get images coded base64

<p:accordionPanel widgetVar="panel" collapsible="true" id="panelApplets">
<p:tab title="Fun 1" id="tabFun1" >
    <h:panelGrid columns="2" cellpadding="10">
        <div id="applet1">
            <applet id="appletFun1"
                    codebase="../applets"
                    code="AppletFun1.class"
                    archive="Fun1.jar"
                    width="800"
                    height="540">
            </applet>
        </div>
        <p:inputTextarea id="res_appletFun1" value="#{bean.stringFun1}" style="width:400px;height:200px;" effectDuration="400"/>                        
    </h:panelGrid>
</p:tab>
<p:tab title="Fun2" id="tabFun2">
    <h:panelGrid columns="2" cellpadding="10">
        <div id="applet2">
            <applet id="appletFun2"
                    codebase="../applets"
                    code="Fun2.class"
                    archive="Fun2.jar"
                    width="220"
                    height="300">
            </applet>
        </div>
        <h:inputHidden id="res_appletFun2" value="#{bean.stringFun2}" />
    </h:panelGrid>
</p:tab>
</p:accordionPanel>

My problem is that one of the applets get base64 coded string in corerct fashion, meanwhile other applet doesn´t. Debuging applet that doesn´t work, i found that following line is unable to get JSObject returning jso=null

 JSObject jso = JSObject.getWindow(this);

Both applets are nearly identical. Anybody knows what could be happening? Why JSObject.getWindow(this) returns null?

I´m using jdk. 1.6_037, both applets are JApplet.

Thanks in advance