Mine's a little different. I am currently using the following configuration:
<Configuration>
<Series>
<Items FieldName="OnTimePercent" AggregateFunction="Sum" SeriesName="Totals" ChartSeriesType="COLUMN" FilterFieldName="ProdGrp" />
</Series>
<XAxis FieldName="Period" SortFieldName="ProdGrp" />
<YAxis />
</Configuration>
Thanks,
Todd