Flex DataGrid设置不同行的渲染颜色

<rowColor:RowColorDataGrid id="dategrId"
							   sortableColumns="false"
							   width="100%"
							   height="100%"
							   fontSize="12"
							   dataProvider="{resultArr}"
							   headerHeight="30"
							   rowColorFunction="calcRowColor"
							   textAlign="center">
		<rowColor:columns>
			<mx:DataGridColumn headerText="序号"
							   width="50"
							   dataField="rn"
							   headerRenderer="mx.controls.Label"
							   itemRenderer="mx.controls.Label"/>
			<mx:DataGridColumn headerText="时间"
							   width="155"
							   dataField="dateTime"
							   headerRenderer="mx.controls.Label"
							   itemRenderer="mx.controls.Label"/>
		</rowColor:columns>
	</rowColor:RowColorDataGrid>

             /**
             * 对DataGrid每行进行遍历，进行自定义的行渲染
             * **/
            private function calcRowColor(item:Object,rowIndex:int,dataIndex:int,color:uint):uint
            {
                var dt:String=item.categoryId;
                if (dt == "31" || dt == "21")
                {
                    return 0xffdcdc;
                }
                else if (dt == "32" || dt == "22")
                    return 0xffe0ab;
                else if (dt == "33" || dt == "23")
                    return 0xffabab;
                else if (dt == "34" || dt == "24")
                    return 0xabffc7;
                else if (dt == "11")
                    return 0xabc5ff;
                else
                    return null;
            }