There is something wrong with the splitting function of Dynamo. For example in this case, when i split the closed curve using the parameters i extracted from four points. The resulting curve is longer than it is supposed to be (list item number 2). However, when i round up the parameters to 10, the curve is ok. if i round up the parameters to 12, the curve has the problem again. I attach the dynamo file here and the link to download revit
Download link: https://drive.google.com/open?id=0B45kxUBszzEBa3ItSDFFWWRvNHM
Thanks!
Typically the parameters of a curve are measured on a scale of 0 to 1. Try using the parameter at point node inputting the main curve and your end points. Then try splitting the curve by parameter, see what you get 
Even splitting by parameter within your reference file is throwing up a:
“Warning: Curve.SplitByPoints operation failed. Curve join produced more than one WIRE in PolyCurve”
The best you might hope for with this geometry is to convert it to a Nurbs.Curve with a degree that Revit can handle for each segment.
(D1.3) Splitting Error NurbsCurve Solution.dyn (42.2 KB)
