I have defined the button like this:
$mform->setHelpButton($newElement, array($newElement, get_string($newElement.'modform', 'khronos')), 'khronos');
If you are using Moodle 2.x, then you should replace the old setHelpButton with the new addHelpButton.
If your are doing development, then you should have Debugging set to DEVELOPER level, and if you do that, you will get helpful messages about deprecated functions like this.
Sorry, I did not say that I am developing a module for Moodle 1.9. I have the system in Debugging mode yet.
http://docs.moodle.org/dev/Places_to_search_for_lang_strings#Adding_language_support_to_a_plugin
You need to put the help in
mod/khronos/lang/en_utf8/help/khronos/labels.html
Thanks Tim! But It continues showing me that couldn't found the file, I'm on Linux, do you know if I need to give some privileges of reading, writing or executing?
Merry Christmas!
All moodle files should be marked like this on Linux:
chown -R root:<web server group> <moodle location>
chmod -R u=rwX,g=rX,o= <moodle location>
for example on redhat based distros web server group is apache.