Hello, I still can't figure out how to run TWL on slick canvas game mode

here are some codes from my game, am I doing something wrong? I will really appreciate it if someone can guide me to the right path. My game runs with those comment outs but when I remove them it shows plain black screen without an error message.
Code:
object Client extends BasicGame(""){
// Variables to create frame and canvas with slick Basic Game
val frame = new JFrame"")
val canvas = new CanvasGameContainer(this)
// For TWL GUI
var theme:ThemeManager=null
var gui:GUI=null
var root:Widget=null
var twlInputAdapter:TWLInputAdapter=null
var lwjglRenderer:LWJGLRenderer=null
def start(path:String,isPrototype:Boolean){
frame.add(canvas)
frame.setSize( new Dimension(800, 600))
frame.setVisible(true)
canvas.start()
}
Code:
def init(gc:GameContainer){
gc.setAlwaysRender(true)
gc.setVSync(false)
root = new Widget();
root.setTheme("");
GL11.glPushAttrib(GL11.GL_ALL_ATTRIB_BITS)
lwjglRenderer = new LWJGLRenderer();
// theme = ThemeManager.createThemeManager(this.getClass().getResource("simple.xml"), lwjglRenderer);
// gui = new GUI(root, lwjglRenderer);
// gui.applyTheme(theme);
GL11.glPopAttrib();
// twlInputAdapter = new TWLInputAdapter(gui, gc.getInput());
// gc.getInput().addPrimaryListener(twlInputAdapter);
}