Setting Color2 works on the first effect, but not subsequent effects

Sub blinkShape(ByRef myShape As Shape)
    Dim myEffect As effect
   
    With ActivePresentation.Slides(1)
        Set myEffect = .TimeLine.MainSequence.AddEffect(myShape, msoAnimEffectChangeFillColor)
        With myEffect
            .EffectParameters.Color2.RGB = RGB(255, 255, 255)
            .Timing.Duration = 1
            .Timing.TriggerType = msoAnimTriggerWithPrevious
            .Timing.AutoReverse = msoTrue
        End With
    End With
End Sub