App Pack isn't meant to be installing channels. They give you the apps to be run from HBC.
Some of the .wad files in chapter 2 are forwarders that will install channels that will launch the apps on the SD card, so if you missed that, then recheck ModPack.zip in chapter 2.
But chapter 3 doesn't install anything to the system menu. Only gives you the apps to be launched from HBC.