checkmol: 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/lib/wims/other/bin/checkmol - from package: wims
/var/lib/wims/other/bin/checkmol - from package: wims
/var/lib/wims/public_html/bin/checkmol - from package: wims

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

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