Custom buttons aren't displaying on my UI - user-interface

Question

I'm creating a simple blackberry application for testing purposes and my custom buttons do not show on the UI of the simulator.
I've created a custom button called CustomButtonField and here is the code:
package test.expense;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.Graphics;
public class CustomButtonField extends Field {
String label;
int backgroundColor;
int foregroundColor;
public CustomButtonField(String label, int backgroundColor, int foregroundColor, long style){
super(style);
this.label = label;
this.backgroundColor = backgroundColor;
this.foregroundColor = foregroundColor;
}
public int getPreferedHeight(){
return getFont().getHeight() + 8;
}
public int getPreferedWidth(){
return getFont().getAdvance(label) + 8;
}
protected void layout(int width, int height) {
setExtent(Math.min(width, getPreferredWidth()), Math.min(height, getPreferredHeight()));
}
protected void paint(Graphics graphics) {
graphics.setColor(backgroundColor);
graphics.fillRoundRect(1, 1, getWidth()-2, getHeight()-2, 12, 12);
graphics.setColor(foregroundColor);
graphics.drawText(label, 4, 4);
}
}
And here is where I invoke it and display it:
HorizontalFieldManager buttonManager = new HorizontalFieldManager(FIELD_RIGHT);
CustomButtonField btnCancel;
CustomButtonField btnSubmit;
public ExpenseSheetScreen() {
super();
btnCancel = new CustomButtonField("Cancel", Color.WHITE, 0x716eb3, 0);
btnCancel.setChangeListener(this);
btnSubmit = new CustomButtonField("Submit", Color.WHITE, 0x716eb3, 0);
btnSubmit.setChangeListener(this);
buttonManager.add(btnCancel);
buttonManager.add(btnSubmit);
add(buttonManager);
}// End Expense Sheet Screen.
What am I doing wrong?

Answer 1

protected void layout(int width, int height) {
setExtent(Math.min(width, getPreferredWidth()),
Math.min(height, getPreferredHeight()));
}
setExtend is set to 0, 0 all the time.