icewmtray-experimental: 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

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/icewmtray-experimental - from package: icewm-experimental

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