Flex ToggleButtonBar label abbreviation

Hi, I have a little problem using the ToggleButtonBar in Flex.

This is my code:

<mx:ToggleButtonBar id="buttonBar">
		
		<mx:dataProvider>
			<mx:Array>
				<mx:String>LABEL ONE</mx:String>
	            		<mx:String>LABEL TWO</mx:String>
			</mx:Array>
        </mx:dataProvider>

	</mx:ToggleButtonBar>

The problem is that when I launch my Flex app, the button that is selected at the beginning (default 0), displays an abbreviated label… for example if I run the previous code I’d get

| LABE… | LABEL TWO |

which is not wanted… how can I avoid this? The label gets fixed when I mouse over the element or when I select another button from the bar.