NVIDIA GameWorks Integration

Could anyone tell me why visual studio is failing to build branch VXGI-4.15?

the error below.

Error C4596 ‘RHIVXGIGetGPUTime’: illegal qualified name in member declaration UE4 D:\Program Files\Epic Games\vgix\UnrealEngine\Engine\Source\Runtime\Windows\D3D11RHI\Private\D3D11RHIPrivate.h 561

Thanks