yplan: 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/yplan - from package: texlive-latex-extra

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

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