System Agent in the New DB

In Vantage 8.0 We encounter the the following problem , We are created
a new DB(Blank DB) which copy from the Epicor Production DB , I confirm
that all AppServer and Database setting in Progress Explorer are same
exclude PORT , and also Add a System Agent in utilitie and it can start
normlly , but we found that thet system agent will be auto stop after
few hours result in printing fail , and the training DB and production
DB haven't this problem , any body experience in this. please advise ,
any information are appreciated. thanks !