Getting the error as: 'MethodImplOptions' does not contain a definition for 'InternalCall' while building a MixedRealityToolKit app for hololens (trying to use a kinect)

Hello, I am getting the error in Unity while building app for the hololens as: "Assets\KinectScripts\KinectWrapper.cs(273,39): error CS0117: 'MethodImplOptions' does not contain a definition for 'InternalCall' " As I said in the header I am trying to use Kinect for a MixedRealityToolikt project for hololens. Actually I am trying to modify MixedReealityToolKit codes. Unity simulation works perfect. It gets data from kinect and displays jointpoints of human body on screen.

I tried to solve this error by changing the code in "Kinectwraper.cs" which is :

 public interface INuiFrameTexture
     {
 
         [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
         [PreserveSig]
 
 
         int BufferLen();
         [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
         [PreserveSig]
 
         int Pitch();
         [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
         [PreserveSig]
 }

with this:

 public interface INuiFrameTexture
     {
 
         [MethodImpl(4096)]
         int BufferLen();
         [MethodImpl(4096)]
 
         int Pitch();
         [MethodImpl(4096)]
         int LockRect(uint Level,ref NuiLockedRect pLockedRect,IntPtr pRect, uint Flags);
          [MethodImpl(4096)] 
         int GetLevelDesc(uint Level, ref NuiSurfaceDesc pDesc);
         [MethodImpl(4096)]
         int UnlockRect(uint Level);
     }

And then I get this error:

Assets\KinectScripts\KinectWrapper.cs(273,21): error CS1503: Argument 1: cannot convert from 'int' to 'System.Runtime.CompilerServices.MethodImplOptions'

Again, Unity simulation works perfect in both codes, but when I am trying to build the app for hololens I get the error. Thank you for your help