Is it possible to use mx.controls in ActionScript class?

Question

I am very new to Flex, with a very small amount of experience in ActionScript so forgive me if the answer to this is obvious. I've tried searching and haven't found a conclusive solution to my problem.
I have a Flex project that I am building in Flex Builder 3. The main application is in mxml, but most of the classes I'm using are in ActionScript.
The general purpose of the application is to create a flowchart that accepts certain inputs on the elements in the charts. The chart components are all ActionScript classes. I am attempting to add a combobox to a component, but despite not getting any errors or warnings I can't get the combobox to show up.
Here's a simplified version of the code within the class (I've left out the stuff that doesn't directly relate to my issue):
    import mx.controls.ComboBox;
          newComboBox = new ComboBox();
          newComboBox.initialized = true;
          newComboBox.alpha = 1;
          newComboBox.dataProvider = valueArray;
          newComboBox.x = 5;
          newComboBox.y = -5;
          newComboBox.height = 20;
          newComboBox.width = width - 60;
          newComboBox.visible = true;
          addChild(newComboBox);

Answer 1

Just realized I hadn't thanked anyone for the suggestions yet. I appreciate it.
Srirangan wrote:
Few points I can think of:
1. Try without the ".initialized = true;" property being set
2. Check if the x & y property values for the ComboBox are valid
3. Check if any styles are being applied that set the top, right, bottom or left properties thru CSS
Removing (or alternately adding) the ".initialized = true" doesn't make a difference. It was actually a last ditch effort to try to make it draw it and wasn't meant to stay in the code.
The x and y property values are valid as far as I know. The code for the positioning and sizing of the combobox was taken from the textfield below which I ended up moving down when I decided to add the combobox. The textfield has always drawn correctly.
I looked through the CSS and it doesn't appear to set top, right, bottom or left anywhere. The only CSS in the project is from the Degrafa library that I'm using to draw components.
Michael Borbor wrote:
What's the val of the variable  width?
Width is set to 150, which is the width of the Constant component.
ATIF FAROOQ wrote:
can you show the hierarchy of your flowchart component
I'm not 100% sure this is what you mean, but it's:
Sprite > Graphic (Degrafa class) > GeometryGroup (Degrafa class) > ComponentGroup > Constant
and just for reference the component's being drawn onto:
UIComponent > Surface (Degrafa class) > SurfaceComponent