UGNX .net API: How to get the parameter range of a curve?

static public void GetCurveParamRange(Tag CurveTag, 
               out double MinPara,
               out double MaxPara)
{
       UFSession gUfSession = UFSession.GetUFSession();
       IntPtr evaluator;
       double[] pararm_range = new double[2];
       gUfSession.Eval.Initialize(CurveTag, out evaluator);
       gUfSession.Eval.AskLimits(evaluator, pararm_range);
       MinPara = pararm_range[0];
       MaxPara = pararm_range[1];
       gUfSession.Eval.Free(evaluator);
}