labltk: 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/labltk - from package: ocaml-labltk

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

On Debian possible default full paths are:

/usr/bin/labltk - from package: ocaml

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

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