LED notification issues htc 816

[the rock 2016]

plz help me ,, i have htc 816 and its ok till now ,, but i found a problem ,, when i receive a message or missed call the led notification working for only 3 minutes then its turned off by itself without i unlock the phone .. and i tried a lot of programs like LED Notifier On and nothing happened
is there anyone has the same issue ??
may anyone help me ??

 

[mumfoau]

Does your particular variant have the option to go into settings-my device-led notification and make adjustments?

 

[the rock 2016]

no .. led notification setting just fields to check or uncheck the things what i need to make led enable for them