[Flex] Spark DataGrid Html ItemRenderer rowheight

<s:DataGrid id="dg" width="100%" height="100%" dataProvider="{acDGData}" variableRowHeight="true">
     <s:columns>
          <s:ArrayList>
             <s:GridColumn headerText="no." dataField="no"/>
             <s:GridColumn headerText="社員名" dataField="name"/>
             <s:GridColumn headerText="お知らせ" dataField="news" >
                 <s:itemRenderer>
                    <fx:Component>
                        <s:GridItemRenderer>
                            <mx:Text htmlText="{data.news}" width="100%" height="100%"/>
                        </s:GridItemRenderer>
                    </fx:Component>
                </s:itemRenderer>
            </s:GridColumn>
          </s:ArrayList>
     </s:columns>         
 </s:DataGrid>

[Bindable]
public var acDGData:ArrayCollection = new ArrayCollection([{no:1,name:"管理者",news:"お知らせテスト"},{no:2,name:"管理者",news:"お知らせテスト２"}.......]);