yaskkserv_simple: 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/sbin/yaskkserv_simple - from package: yaskkserv

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