NVML_ERROR_UNKNOWN while calling nvmlInit()

Developer Tools Other Tools System Management and Monitoring (NVML)
1

I’m trying to get gpu memory info in my C++ project. (win10, cuda 10.0, visual studio 2015)
And I failed to initialize NVML.( NVML_ERROR_UNKNOWN )
However, nvidia-smi works. So I don’t really know what’s the problem.

Any idea how to fix this?