gnome-at-properties: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/gnome-at-properties - from package: control-center

You may install the required package with command yum install {package}
Error in other languages:
gnome-at-properties: bevel nie gevind nie
gnome-at-properties: comandă negăsită
gnome-at-properties: comando não encontrado
gnome-at-properties: commande introuvable
gnome-at-properties: command not found
gnome-at-properties: käsku ei ole
gnome-at-properties: không tìm thấy lệnh
gnome-at-properties: komanda nerasta
gnome-at-properties: Kommando nicht gefunden.
gnome-at-properties: kommandot finns inte
gnome-at-properties: komut yok
gnome-at-properties: nie znaleziono polecenia
gnome-at-properties: níor aimsíodh an t-ordú
gnome-at-properties: no se encontró la orden
gnome-at-properties: no s'ha trobat l'ordre
gnome-at-properties: opdracht niet gevonden
gnome-at-properties: parancs nem található
gnome-at-properties: perintah tidak ditemukan
gnome-at-properties: príkaz nenájdený
gnome-at-properties: příkaz nenalezen
gnome-at-properties: команда не найдена
gnome-at-properties: командата не е открита
gnome-at-properties: 命令找不到
gnome-at-properties: コマンドが見つかりません