qucstrans: 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 CentOS possible default full paths are:

/usr/bin/qucstrans - from package: qucs

You may install the required package with command yum install {package}

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