[c-nsp] EEM event-manager and "event none" question.

[luismi]

I have this code...

event manager applet A-EU-UP
 event track 10 state up
 action 1.0 syslog msg "Track 10 Up. Houston we don't have a problem"
 action 2.0 cli command "enable"
 action 3.0 cli command "conf t"
 action 4.0 cli command "<some commands here>"

I tried to execute...
# event manager run  A-EU-UP
Embedded Event Manager policy EU-ACEL-BACKUP-OFF not registered with
event none Event Detector

What is the reason for that message?
Looks like the EEM code is not running.
As far as I can read at documentation found with google, I need "event
none" at the beginning of the applet, but, what is the reason for it?
When "event none" must be used?