fillmask: 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

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/voxbo/bin/fillmask - from package: voxbo

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