expeyes-junior-doc: 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/expeyes-junior-doc - from package: expeyes-doc-common

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