Hello thespacepope,
You have run into what can happen when you have broadcasts in different bands when you have a single band antenna.
TV broadcasts in the US currently are in 3 bands: low-VHF (real channels 2-6), high-VHF (real channels 7-13) and UHF (real channels 14 and up).
Your 4221 is exclusively UHF and not designed for real channels (RF) 9 and 11.
There are non-drilling options for roof mount antennas such as chimney mounts. Outdoors your 4221 while UHF, may receive RF channels 9 and 11. It's not uncommon in very good signal access areas that UHF exclusive antennas reliably receive VHF signals.
If you must be in the attic, I'd suggest you purchase an antenna that supports high-vhf and UHF. Swap out your CM-4221 for an
Antennacraft HBU22.
http://www.solidsignal.com/pview.asp?p=hbu22. Orientate antenna to magnetic 25 degrees or so.
You may have to play with aiming to receive signals at magnetic 52 through 62 while receiving ION from magnetic 330.
I wouldn't suggest an amplifier unless you are running long leads of coax. You have very good signal strength and most of the green shaded signals should be doable from your attic.
Your issue was an antenna that supported high-VHF and UHF instead of UHF only.