I've a simple function, copied from various examples on the net, to sum
numbers based on the color of another cell. I want change the active cell
color but it doesn't seem to work. Any suggestions, any help appreciated,
code is as follows...

Function ColorSum(cRefColor, rRange)
Dim r As Range
Dim iColorIndex As Integer

ColorSum = 0

iColorIndex = cRefColor.Font.ColorIndex

'build formula for range
For Each C1 In rRange.Cells
If C1.Font.ColorIndex = iColorIndex Then
ColorSum = ColorSum + C1.Value
Else
C1.Font.ColorIndex = iColorIndex
End If
Next

'this doesn't work!
ActiveCell.Font.ColorIndex = iColorIndex

End Function