Problem setting RGB Values with ShapeRange

[Bob Gibbons]

I am trying to usa a VBA macro in Excel to set the interior color of a
cell to a specific RGB value. I want to show a user the apparent color
of a computed RGB value with an accompanying cell or box.

My initial thought was to pick the RGB value from the cells adjacent
to the cell I was trying to color with the following code.

Sub Macro2()
R = ActiveCell.Offset(0, -3)
G = ActiveCell.Offset(0, -2)
B = ActiveCell.Offset(0, -1)
With Selection.Interior
.Color = RGB(R, G, B)
.Pattern = xlSolid
End With
End Sub

This macro works exactly as I hoped, with the exception of the well
know problem that the color set is not the specific RGB value, but
rather the RGB color of the closest match in the color table.

Microsoft Knowledge Base Article 71781 (or 213201), "RGB Function May
Map to Unexpected Color" refers to this problem, and suggests the use
of the ShapeRange object collection instead to get around this
problem.

I tried this with the following code,

Sub Macro2()
R = ActiveCell.Offset(0, -3)
G = ActiveCell.Offset(0, -2)
B = ActiveCell.Offset(0, -1)
With Selection.ShapeRange.Fill.ForeColor.RGB =
RGB(R, G, B)
End With
End Sub

But get an error on the Selection Line.

I am not a VB programmer so am clueless as to what I am doing wrong.

Will the ShapeRange command only work on an inserted Shape rather than
a spreadsheet cell? This is OK, I can insert a rectangular box, but
how do I refer to the cells containing the RGB values?

Any help is much appreciated.

Bob