public GradingTargetType Target { get; set; }

Public Property Target As GradingTargetType
	Get
	Set

public:
property GradingTargetType Target {
	GradingTargetType get ();
	void set (GradingTargetType value);
}

Must set the Target correctly before you getting or setting properties which are related to the target(like CutSlope/Slope/FillSlope) in the GradingCriteria.