OTA digital antenna reception - problem

I just installed a new HDTV OTA directional antenna (non-amplified) on my roof. I aimed it at 48 degrees, according to this chart for Santa Monica, CA. Theoretically, all the stations should come in cleanly since they're all broadcast from the same place, Mt. Wilson. So much for theory! I need to aim the antenna in different directions to pick up different stations. When they come in, the quality is excellent. But, I can't get them to all come in together. What's going on? The stations still come in w/o being amplified so that shouldn't be the problem - should it? Even if I was to get an amplified antenna, getting electricity up to the roof wouldn't be easy. Suggestions?
You can use an inline amplifier. It doesn't have to be on
the roof. Some units come with a special splitter that will
allow you to run power out to the amplifier over coax and
receive signal over the same coaxial cable.

Inside the home you'll have this splitter that will have one
output for the TV and one input for a transformer to feed
the amplifier outside. This is the simplest way to get
remote power to your amplifier without having the power
connection outside.

Chances are once you get the amplifier installed, all your
channels will come in cleanly.
Try using a high quality UHF antenna.Seems to work better than a large VHF .
The inline amp seemed like a great idea. Just installed it after a visit to Fry's. The good news is that an already excellent picture has improved even more - almost 3D like. It's as if the soundstage just widened and deepened. The bad news is that the original problem still exists.
You need to piggy back another antenna aimed in the direction
of the other channels you desire. The signals can be very
directional from my experience. Piggy back and tie in to your
existing coaxial input. Hopefully that should put the problem
to rest.
Here try this TV signal locator TV Fool
Gmood1-Great site. Much better than the other. Thanks!
After much research, I think I discovered the problem. Bottom line is that I need either two antennas facing different directions w/a VHF-UHF combiner module or an omnidirectional antenna. I'll probably do the omni.

The problem in L.A. is that a few of the stations are transmitting on VHF while most of the others are on UHF. The VHF stations have also cut down on their broadcast power. Even though all the signals originate from the exact same place, oddly enough, I was able to pick up the VHF stations with my UHF antenna but only when I aimed it 90 degrees off axis. These must be signals that are 'skipped'. Allegedly, the VHF stations (such as KABC) are requesting to increase their power but need to get FCC permission first so that they don't interfere with some other signals. It could take up to a year for government approval to do so.

As Roseannadana's daddy use to say, 'It's always something'.