Make autoshape automatically change color

Hi everyone,
I am currently working on a small project and I need an autoshape to automatically change color based on a cell value. I have an attached example and in this case it's cell B8. B8 sums up data from cell B3:B6. I've created the code, but the autoshape won't automatically change color. I need to double click on B8 and press enter, then the color changes.
Any ideas what might be wrong?

Here's my code:

Private Sub Worksheet_Change(ByVal Target As Range)

'Macro purpose: Make autoshape change color based on value in cell B8
    If Not Intersect(Target, Range("B8")) Is Nothing Then
               If IsNumeric(Target.Value) Then
            If Target.Value < 10 Then
                ActiveSheet.Shapes("Oval 1").Fill.ForeColor.RGB = vbGreen
            ElseIf Target.Value >= 20 And Target.Value < 30 Then
                ActiveSheet.Shapes("Oval 1").Fill.ForeColor.RGB = vbYellow
            Else
                ActiveSheet.Shapes("Oval 1").Fill.ForeColor.RGB = vbRed
            End If
        End If
    End If
End Sub

Thanks

It worked like a charm.

Thanks so much,
Amar.