AUTO SUM ONLY SPECIFIC COLORED CELLS BY CONDITIONAL FORMATING

HI EVERY ONE
I HAVE THIS EVENT CODE FOR SUMMING DEFINED RANGE

Private Sub Worksheet_Change(ByVal Target As Range)
Dim RNG1 As Range
Dim RNG2 As Range
Set RNG1 = Range("D220")
Set RNG2 = Range("D21")
If Not Intersect(RNG1, Target) Is Nothing Then
RNG2.Value = Application.WorksheetFunction.Sum(RNG1)
End If
End Sub


BUT WHAT I NEED URGENT TO ADD A CONDITION TO SUM (ONLY) AS EXAMPLE ALL
Cells.Interior.ColorIndex = 3 I CONTROL WITH CELLS COLOR WITH
CONDITIONAL FORMATING I HOPE ITS VERY CLAER , I HOPE ANY ONE CAN HELP
APPRECIATED