dbsessmgr: 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/dbsessmgr - from package: mono-xsp

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

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