[C#]i can't create UserTracker instance

Hi all, i am new to nuitrack and want to develop skeleton tracking application with C#.
but, i have a big problem.
i just copied “nuitrack_csharp_sample” to my new VS2017 project and The result is as follows:

However, DepthSensor and ColorSensor are created successfully.
i don’t know what is wrong.

My development environment is,

OS : Windows 10 EDU (Ver.1803)
IDE : Visual Studio 2017
Language : C#
Sensor : RealSense D435i (FW :
Nuitrack : 0.29.0
Nuitrack SDK : 1.4.1

Anyone knows how to resolve this issue ?