treeview.dll: 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/share/asp.net-demos/bin/treeview.dll - from package: asp.net-examples

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

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