xmms2tray: 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/xmms2tray - from package: xmms2tray

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

Error in other languages:
xmms2tray: bevel nie gevind nie
xmms2tray: comandă negăsită
xmms2tray: comando não encontrado
xmms2tray: commande introuvable
xmms2tray: command not found
xmms2tray: käsku ei ole
xmms2tray: không tìm thấy lệnh
xmms2tray: komanda nerasta
xmms2tray: Kommando nicht gefunden.
xmms2tray: kommandot finns inte
xmms2tray: komut yok
xmms2tray: nie znaleziono polecenia
xmms2tray: níor aimsíodh an t-ordú
xmms2tray: no se encontró la orden
xmms2tray: no s'ha trobat l'ordre
xmms2tray: opdracht niet gevonden
xmms2tray: parancs nem található
xmms2tray: perintah tidak ditemukan
xmms2tray: príkaz nenájdený
xmms2tray: příkaz nenalezen
xmms2tray: команда не найдена
xmms2tray: командата не е открита
xmms2tray: 命令找不到
xmms2tray: コマンドが見つかりません