newicktops: 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/bin/newicktops - from package: njplot

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

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