Volume Amplification does not work

Hi,I noticed that the Volume Amplification does not work in video player, i am watched Movies with AC3-6ch, AC3-2ch, mp3 audio, sometimes I had to make the sound louder , but there is no response to the movement of the slider of Volume Amplification in KODI ( probably OMX Player ).
I have Raspberry PI1 B with HDMI output to TV.
I tried 7.0 and 7.02 releases, but Amplification has never worked.

In OpenElec or OSMC this feature works correctly.
I hope you fix this bug in the next release.
Sorry for my poor english.

Quote from popcornmix

Do you have passthrough enabled? (That will stop amplification from working).
Does it work better with omxplayer disabled?

Hi,
I have not touched standard audio settings in KODI, passthrough is disabled of course.
As far as i know, on RPi1 OMX Player cannot be disabled. In my Video Settings both
items: Hardware Acceleration OMX/MMAL are turned on. ( same as in OSMC/OpenELEC ).
I'm not sure if this has anything to do with the sound.