actmerge: 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/lib/news/bin/actmerge - from package: inn2
/usr/lib/news/bin/actmerge - from package: inn

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

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