[flexcoders] itemRenderer's width and color is not changed. why?

[luoxuanhuayelin]

 <mx:DataGridColumn width="48"  headerText="ADD" editable="false">
   <mx:itemRenderer>
   <mx:Component>
     <mx:Button label="add"   color="#0000FF"  width="20"  
click="AddItem()">
    </mx:Button>                   
    </mx:Component>
    </mx:itemRenderer>
  </mx:DataGridColumn>

 I have setted the  color="#0000FF"  width="20" ,but not changed in 
explorer?  the width of Button is still 48, How can do?