Setting chart series color

I am running Excel 2004 for the Mac on OSX 10.5.2.

I would like to set the color of a chart series from RGB values stored
in cells of the worksheet.

I recorded a macro to get this piece of code:

ActiveSheet.ChartObjects("Chart 1").Activate
    ActiveChart.ChartArea.Select
    ActiveChart.SeriesCollection(7).Select
    With Selection.Border
        .Color = RGB(0, 0, 0)
        .LineStyle = xlNone
        .Transparency = 0
    End With
    With Selection
        .MarkerBackgroundColor = RGB(252, 243, 5)
        .MarkerForegroundColor = RGB(252, 243, 5)
        .MarkerStyle = xlSquare
        .Smooth = False
        .MarkerSize = 5
        .Shadow = False
        .MarkerTransparency = 0
    End With

The given RGB values are from the color picker, I would read them in
from the worksheet.

The problem is that if I manually change the color, and then run the
macro the color remains the one that I manually chose not the one
prescribed in the macro. If I change the Markersize to something other
than 5, that change is made. What gives????