gv2gml: 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/gv2gml - from package: graphviz

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

Error in other languages:
gv2gml: bevel nie gevind nie
gv2gml: comandă negăsită
gv2gml: comando não encontrado
gv2gml: commande introuvable
gv2gml: command not found
gv2gml: käsku ei ole
gv2gml: không tìm thấy lệnh
gv2gml: komanda nerasta
gv2gml: Kommando nicht gefunden.
gv2gml: kommandot finns inte
gv2gml: komut yok
gv2gml: nie znaleziono polecenia
gv2gml: níor aimsíodh an t-ordú
gv2gml: no se encontró la orden
gv2gml: no s'ha trobat l'ordre
gv2gml: opdracht niet gevonden
gv2gml: parancs nem található
gv2gml: perintah tidak ditemukan
gv2gml: príkaz nenájdený
gv2gml: příkaz nenalezen
gv2gml: команда не найдена
gv2gml: командата не е открита
gv2gml: 命令找不到
gv2gml: コマンドが見つかりません