wmcalclock: command not found

Have You tried accessing the binary with the full path?

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/wmcalclock - from package: wmcalclock

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