Connecting an LG sound bar to a genie directv remote

I have been able to program my TV to the genie remote and I am able to control the on/off and the volume on my TV and I am also able to turn my sound bar on with the genie remote but it will not control the volume.  I have tried going to settings and choosing remote, audio equipment, chosen LG and followed the prompts with the codes provided but none of them work.  Please help because I know there is a way to do this but I am at a loss.