ns-inactivate: command not found

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 Debian possible default full paths are:

/usr/sbin/ns-inactivate - from package: 389-ds-base

You may install the required package with command apt-get install {package}

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