dcmsign: 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/dcmsign - from package: dcmtk

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

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