can't make the nvidia driver work

Hello, when I am starting the xserver, the nvidia driver won't load:

NVIDIA: could not open the device file /dev/nvidiactl (No such file or directory).

I have booted the system with enable_nvidia="YES". I have also manually upgraded the nvidia driver to 188.22 which is the only one who support my graphics card.

What can be the issue?
You need to have:
in your /boot/loader.conf

You can check if it's loaded with kldstat. To load it now kldload nvidia.
Most of the stuff in rc.conf is enable_*. In loader.conf it's mostly *_load ;)
If you forget, you can always take a look at the defaults:

But whatever you do, do *not* edit these files.