netexport does not create HAR file

[Arie Hoenel]

 File firebug = new File(System.getProperty("user.dir") + "\\src\\test\\resources\\firebug-2.0.6.xpi");//firebug-1.7.2.xpi
        File netExport = new File(System.getProperty("user.dir") + "\\src\\test\\resources\\netExport-0.9b6.xpi");//netExport-0.8b9.xpi

        FirefoxProfile profile = new FirefoxProfile();
        try {
            profile.addExtension(firebug);
            profile.addExtension(netExport);
        } catch (IOException e) {
            e.printStackTrace();
        }

        profile.setPreference("app.update.enabled", false);

        //Setting Firebug preferences
        profile.setPreference("extensions.firebug.currentVersion", "2.0");
        profile.setPreference("extensions.firebug.addonBarOpened", true);
        profile.setPreference("extensions.firebug.console.enableSites", true);
        profile.setPreference("extensions.firebug.script.enableSites", true);
        profile.setPreference("extensions.firebug.net.enableSites", true);
        profile.setPreference("extensions.firebug.previousPlacement", 1);
        profile.setPreference("extensions.firebug.allPagesActivation", "on");
        profile.setPreference("extensions.firebug.onByDefault", true);
        profile.setPreference("extensions.firebug.defaultPanelName", "net");
        profile.setPreference("extensions.firebug.netFilterCategories", "image");
        // Setting netExport preferences
        profile.setPreference("extensions.firebug.netexport.alwaysEnableAutoExport", true);
        profile.setPreference("extensions.firebug.netexport.autoExportToFile", true);
        profile.setPreference("extensions.firebug.netexport.Automation", true);
        profile.setPreference("extensions.firebug.netexport.showPreview", false);
        profile.setPreference("extensions.firebug.netexport.pageLoadedTimeout", 500);
//        profile.setPreference("extensions.firebug.netexport.saveFiles", true);
        profile.setPreference("extensions.firebug.netexport.defaultLogDir", "C:\\Workspace\\CaptureNetworkTraffic\\");

What I missed ? why does it did not create the file ?

Thank