Tizen Developers

So I'm trying to execute javascript code from native app (in C) and below is the function that keeps failing:

static Evas_Object* load_html_file(Evas_Object* parent)
{
    Evas *e_webview = evas_object_evas_get(parent);
    Evas_Object *browser = ewk_view_add(e_webview);
    Ewk_Settings *settings = ewk_view_settings_get(browser);
    ewk_settings_javascript_enabled_set(settings, EINA_TRUE);

    char* javaScript =
            "function setWallpaperSuccess() {}"
            "function setWallpaperError() {}"
            "function test() {"
            "try"
            "      {"
            "  tizen.systemsetting.setProperty(\"HOME_SCREEN\", \"file:\/\/opt\/usr\/media\/Downloads\/2017-03-20_RiverofLife_1080x1920_no.jpg\", setWallpaperSuccess, setWallpaperError);"
            " }"
            "      catch (error)"
            "      {"
            "         console.log(\"Error: \" + error); return 'exceptionhappened';"
            " } return 'thisworkedorwhat';"
            "}"
            "test();";
    ewk_view_script_execute(browser, javaScript, JScallback, NULL);
    elm_win_resize_object_add(parent, browser);
    evas_object_show(parent);
    evas_object_show(browser);
    return browser;
}

static void JScallback(Evas_Object* o, const char* result_value, void* user_data) {
    dlog_print(DLOG_INFO, LOG_TAG, "[scriptCallback] return value: %s\n", result_value);
}

sdb dlog always prints:

I/    My-Experiment-App    (31448): [scriptCallback] return value: exceptionhappened

And these are privileges declared for native app (TizenManifest file):

    <privileges>
        <privilege>http://tizen.org/privilege/mediastorage</privilege>
        <privilege>http://tizen.org/privilege/network.get</privilege>
        <privilege>http://tizen.org/privilege/systemsettings</privilege>
        <privilege>http://tizen.org/privilege/internet</privilege>
        <privilege>http://tizen.org/privilege/appmanager.launch</privilege>
        <privilege>http://tizen.org/privilege/externalstorage</privilege>
    </privileges>

Could anyone please help me know why is it failing?

Thanks a much and kind regards,

~Viren