enclosing data in a box

I am working on an application where I want to enclose a few check boxes in a box.?SO I have two checkboxes namely:-

X Shop right now

X Shop later

Followed by a button:-

submit

Now what I want is to enclose the two checkboxes in a box and have the submit button just underneath the box.?I have tried

%26lt;mx:Box%26gt;

%26lt;mx:CheckBox width=''100'' id=''a'' label=''Shop right now''/%26gt;

%26lt;mx:CheckBox width=''100'' id=''b'' label=''Shop later''/%26gt;

%26lt;/mx:Box%26gt;

%26lt;mx:Button label=''Update'' click=''showSelected(event)'' styleName=''buttonSkin''/%26gt;

But I dont see the box around the checkboxes visible, I have also tried VBox and Form but to no avail.?any help would be appreciated.