GL4Java in a JFrame

Hi all, i''m trying to design a program in java that draws a simple shape (rectangle, triangle or circle) then the user can choose to translate, scale or rotate that shape.. I created two classes: Transformations and OpenGLPart, the Transformations class is a JFrame containing the control panel for the user and a component with the size of 400x400 in which the openGL part is supposed to appear, and the OpenGLPart class contains the openGL code.. There is a button called applyButton in the control panel, when clicked, the values for scaling, rotating, translating and the required shape are stored then a new object from class OpenGLPart is created with these values as constructor parameters, here''s the code: void draw() { translateX = (float)(translateXSlider.getValue()); translateY = (float)(translateYSlider.getValue()); scaleX = (float)(scaleXSlider.getValue()); scaleY = (float)(scaleYSlider.getValue()); rotate = Float.parseFloat(rotateField.getText()); OpenGLPart ogl = new OpenGLPart(shape, translateX, translateY, scaleX, scaleY, rotate); canvas = (Component)(ogl); layout.add(canvas , BorderLayout.CENTER); contents.revalidate(); } The problem is.. nothing shows.. only empty space.. can anyone help me please? Thanks a lot