I can't get the DirctTV remote to control the sound through the Sony Home Theatre. Can get it to turn on/off. Volume control on DirectTV controller engages the Mitsubishi sound control (set for off).
There is likely to be a lot of codes for the Sony in your Directv manual so I would continue on through the list. In other words the code you stopped at operates the power toggle but is not the correct code. IF another code doesn't solve your problem try the learning mode.
There are four preset slots you can choose on the DirecTv remote. At the top of the remote is a slide switch that you use to select DirecTV box or TV in between those 2 more selection you can use to control your receiver.