Epoptes Configuration over Debian 8.0

Hi guys, This is my first post, and first of all I would like to thanks to listen my concern.

I have perfomed an upgrade from Debian 7.1 to 8.0 over the school laboratory with 14 PCs. I can not set up Epoptes correctly, I perform every step and it seems to be configured in the rigth way but it does not work. Please let me share with you some logs of the client setting up:

This is what EPOPTES-CLIENT file includes:

# The server where epoptes-client will be connecting to.
# If unset, thin client user sessions running on the server will try to connect
# to "localhost", while thin client root sessions and fat or standalone clients
# will try to connect to "server".
# LTSP automatically puts "server" in /etc/hosts for thin and fat clients,
# but you'd need to put "server" in DNS manually for standalone clients.
SERVER=ElProfe.local

# The port where the server will be listening on, and where the client will try
# to connect to. For security reasons it defaults to a system port, 789.
PORT=789

# Set Wake On LAN for devices that support it. Comment it out to disable it.
WOL=g

And this is the rusult of the command EPOPTES-CLIENT -C

alumno@huayra:~$ sudo epoptes-client -c
depth=0 C = AU, ST = Some-State, O = Internet Widgits Pty Ltd
verify error:num=18:self signed certificate
verify return:1
depth=0 C = AU, ST = Some-State, O = Internet Widgits Pty Ltd
verify return:1
DONE
Successfully fetched certificate from ElProfe.local:789

Hope you can help me,

Thanks in Advance,

Walter