how to program an audio receiver that isn't in the list to my genie RC73 remote

If you've tried all of the codes and none of them work, then it's likely that the cheap DirecTV remote can't control it. After all, they can't operate every device on the planet. A quality universal remote, like Logitech Harmony, is the way to go. 

Thanks for responding, but I never said I tried all the codes and none of them worked. What I'm saying is that my receiver is not listed when I go through the onscreen menu for programing an audio receiver. Bottom line, I'm asking if there's a way to get around the fact that my receiver isn't listed?

if you're using a Genie --When asked to program the avr --Select "I don't know my model number" the Genie will automatically try all codes one at a time 

If NOT What Model & type AVR is it? --RCA codes may work (as one example) 

I have the same issue with my Anthem MRX720 and my HR44/200 (Genie Box) I can program the TV model (LG CX65PUA) just fine but the Anthem MRX720 is not listed at all and there is no “my equipment is not on the list” option when I go to program it.

Here’s the thing though IT USED TO WORK! (I had an rc71 remote before but it was in bad shape so I bought a RC73)  What’s odd though is that the Anthem is still listed as an option on my HR24/200 in my office! The only thing I can think of is the HR44 got a software update last week and they changed that functionality somehow 

I feel your pain. See my post above.