Inside you incrontabs, you must leave *only* 1 space between the <path> <mask> <cmd>. If you leave 2 or more spaces, then the 2nd (and more) spaces will be considered part of the <mask> or <cmd> and it will fail… I was leaving 2 spaces between <mask> and <cmd>, and incron did not work and in /var/log/syslog there were these messages
incrond[27693]: cannot exec process: No such file or directory
This was because of having 2 spaces… when I corrected to only 1 space, it began working correctly. Keep it in mind, so you dont suffer as much as I did to find it out 
After editing with “incrontab -e”, check that “incrontab -l” shows the rules. If it does not show some rule, then that is because that rule has some error and was not recognized.
To debug what is happening behind the curtains, its usefull to have a “tail -f /var/log/syslog” on another terminal…
Quoted from https://zipizap.wordpress.com/2013/11/15/incron/
Very useful thanks !
😉 nJoy
Thanks for that! Probable saved hours of checking for me!