The service is running, the configuration file is fine, we just have a bug, as I see it is what it is: wall:
Removes wicd and the solution is quite simple, just like manually configure the network-manager applet so that it starts with the environment
From the lxde menu >> Preferences >> default applications for LXSession
In the boot tab you add a new application that calls the start nm-applet.
The only thing left is to restart the setting and see if it works.
And there would be a sticky and it would be part of the configuration of the user, if more users or create some new ones, also suffer the bug and have to repeat the process each with their own.