Basically you've exceeded the 255 character per line count limit for .ini entries.
RE-read the OP specifically the 'IMPORTANT - Manually adding archives to your Fallout3.ini' bit in the DLC compatibility section for info on shortening the bsa names.
Plus do yourself a favor and get the Little Boy handy utility linked to in that section.
Nope. That wasn't the case. It was like that:
SArchiveList=AII.bsa, Fallout - Textures.bsa, Fallout - Meshes.bsa, Fallout - Voices.bsa, Fallout - Sound.bsa, Fallout - MenuVoices.bsa, Fallout - Misc.bsa, Anchorage - Main.bsa, Anchorage - Sounds.bsa, Unofficial Fallout 3 Patch.bsa, BrokenSteel - Main.bsa, BrokenSteel - Sounds.bsa
And changed it to that to fix the problem with missing firing sound:
SArchiveList=AII.bsa, Fallout - Textures.bsa, Fallout - Meshes.bsa, Fallout - Voices.bsa, Fallout - Sound.bsa, Fallout - MenuVoices.bsa, Fallout - Misc.bsa, Anchorage - Main.bsa, Anchorage - Sounds.bsa, BrokenSteel - Main.bsa, BrokenSteel - Sounds.bsa, Unofficial Fallout 3 Patch.bsa,