Found no NVIDIA driver on your system

CUDA VERSION
cat /usr/local/cuda/version.txt
CUDA Version 7.5.18

PyTorch CUDA VERSION
__version__ = ‘0.3.0.post4’ (pytorch 1.0 does not have cuda75?)
debug = False
cuda = ‘7.5.18’

however, error occur when execute: “model.cuda(gpu_idx)”
AssertionError:
Found no NVIDIA driver on your system. Please check that you
have an NVIDIA GPU and installed a driver from
http://www.nvidia.com/Download/index.aspx

According to the above, the graphics card and driver should exist, how can i do with this problem? thank you!