If the dtv remote is one of the white remotes, try cosdesearch on either av1 or av2 devices, but not by power search by vol instead. Like this:

1. av1 or av2
2. press and hold MUTE & SELECT for two blinks
3. enter 9-9-1, wait two blinks
4. enter 2
5. tap VOL UP and release
6. with TV ON
7. keep pressing and releasing CH UP, if and when the VOLUME changes
8. press SELECT to Lock in code

To punch-through the vol to all evices:

1. av1 or av2
2. press and hold MUTE & SELECT for two blinks
3. enter 9-9-3
4. press SELECT