libval_check_conf: 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 CentOS possible default full paths are:

/usr/bin/libval_check_conf - from package: dnssec-tools

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/libval_check_conf - from package: libval-bin

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

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