qwavfade: 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/qwavfade - from package: quelcom

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

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