[flexcoders] FLEX CHARTING

[kotha poornima]

Hi All,
I am using Column chart in my project. Here i need to plot uptime and downtime 
of the system using column chart. Uptime data will come from the database like 
this:
    <StatusGraph>
        <data>
          <date>10</date>
          <uptime>0</uptime>
        </data>
        <data>
          <date>11</date>
          <uptime>1</uptime>
        </data>
        <data>
          <date>12</date>
          <uptime>2</uptime>
        </data>
        <data>
          <date>07</date>
          <uptime>2</uptime>
        </data>
        <data>
          <date>07</date>
          <uptime>2</uptime>
        </data>
        <data>
          <date>18</date>
          <uptime>0</uptime>
        </data>
      </StatusGraph>
 I am not getting any downtime information from the database. Doubt i have here 
is can i do any calculations before plotting the graph.
 I tried like this. But its not working.
                <mx:ColumnChart id="chart" 
dataProvider="{resultXML.System[0].StatusGraph.data}"                 
type="100%" width="500" height="250" showDataTips="true">
                    <mx:series>
                        <mx:ColumnSeries yField="uptime" />
                       <mx:ColumnSeries yField="100-uptime" /> -- Doubt
                    </mx:series>
                    <mx:horizontalAxis>
                        <mx:CategoryAxis categoryField="date" />
                    </mx:horizontalAxis>
                </mx:ColumnChart>
SO here iam using yfield as 100-uptime to calculate downtime. But its not 
displaying any data. Can any one help me regarding this.

Thanks and Regards,
Poornima