Custom (AUDIO) effects con be applied only on VIDEO TRACK (and not audio track)

For example, create a custom VOLUME(KEYFRAMMABLE) effect, i called it VOLUME 10 (+10 db) after that, trying to apply the effect on a video track (leaving audio track grouped)

if i move the effect to ONLY-VIDEO track , the effect is successfully applied ( +DB on a VIDEO??? ) if i move the effect to AUDIO TRACK, nothing happens.

if i use the defualt VOLUME(KEYFRAMMABLE), it's working on the reversed mode (CORRECTLY).. just applied to AUDIO TRACK.

i think that the custom effect are all created as a VIDEO EFFECTS .. and never as a AUDIO EFFECTS.