libval-config: 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-config - from package: dnssec-tools-libs-devel

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

On Debian possible default full paths are:

/usr/bin/libval-config - from package: libval-dev

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

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