AddThresholdColorRule给出错误Spotfire（Iron Python）

from Spotfire.Dxp.Application.Visuals import *
from Spotfire.Dxp.Application.Visuals.ConditionalColoring import *
from System.Drawing import Color

# Get the visualization reference
for visualization in Document.ActivePageReference.Visuals:
  if visualization.Title == "Test Bar Chart1":
    visualContentObject = visualization.As[VisualContent]()

#Clear default coloring
visualContentObject.ColorAxis.Coloring.Clear()
#set color
visualContentObject.ColorAxis.Coloring.AddThresholdColorRule(StringComparisonOperator.GreaterOrEqual, ConditionValue.CreateLiteral('40'), Color.FromName("Green"))
from Spotfire.Dxp.Application.Visuals import *