wmbubble: 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/wmbubble - from package: wmbubble

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

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