vnccapture: 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/vnccapture - from package: libnet-vnc-perl

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

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