proofserv.bin: 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/proofserv.bin - from package: root-system-proofd

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

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