Nvidia-smi command it return this message : ***No devices were found***

Accelerated Computing CUDA CUDA Setup and Installation
1

Hello sir :

we have Linux Server :

x86_64

DISTRIB_ID=Ubuntu

DISTRIB_RELEASE=20.04

DISTRIB_CODENAME=focal

DISTRIB_DESCRIPTION=“Ubuntu 20.04.6 LTS”

NAME=“Ubuntu”

VERSION=“20.04.6 LTS (Focal Fossa)”

ID=ubuntu

ID_LIKE=debian

PRETTY_NAME=“Ubuntu 20.04.6 LTS”

VERSION_ID=“20.04”

HOME_URL=“https://www.ubuntu.com/”

SUPPORT_URL=“https://help.ubuntu.com/”

BUG_REPORT_URL=“Bugs : Ubuntu”

PRIVACY_POLICY_URL=“Data privacy | Ubuntu”

VERSION_CODENAME=focal

UBUNTU_CODENAME=focal
kernel : 5.15.0-100-generic

after install cuda toolkit and run nvidia-smi command
it return this message :
No devices were found
can you help us please :
best regards