[flexcoders] which HSlider event can change showDataTip value?

[markflex2007]

Hi;

I want to disable the datatip show in some value,I use thumbDrag event,but it 
seems the showDataTip not change.

<mx:HSlider id="radius"   width="300" minimum="0.5"   maximum="5"  
tickColor="0x323232"   snapInterval="0.5" tickInterval="0.5" 
dataTipPrecision="1" labels="['0.5 mile','5 miles']" liveDragging="true" 
thumbDrag="radiusAdjust()"    
dataTipFormatFunction="radiusDataTipFunc"  showDataTip="false"/>
     
private function radiusAdjust():void{                           
if(radius.value == 1.5 || radius.value == 2.5){                            
  radius.showDataTip = false;                             
}else{
  radius.showDataTip = true;
}                   

}

Please let me know which event can update showDataTip.

Thank you for your help

Mark