Pivot Chart Trendline?

[Ken]

Excel2003 ... when my Pivot Chart is Type "Column" ... I have ability to add
a "Trendline" ... However, when I change my Chart Type to a "Stacked Column"
.... "Trendline" is now grayed out???

So ... is there a way to add a "Trend Line" to a Pivot Table "Stacked
Column" Chart?

Thanks ... Kha