dckey: 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/dckey - from package: dicom3tools

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

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