My initial reaction is that the signals should be strong enough (according to your report) to be picked up easily by an outdoor 4228, and especially if there's a good pre-amp also being used.
Here are a few comments/suggestions:
1) Make sure the analyzed location is accurate for your house. Sometimes, address lookups are not all that accurate (varies from one city to the next depending on the quality of the database sources). You can check the accuracy by using the Interactive Maps tool (
here). It will show a map after you enter your address and if the location is not quite right, you can drag-n-drop the pointer until it's right on top of your house. If the initial address lookup is significantly different than your true location, there might be big differences in the analysis results.
You can also play what-if games with antenna heights by changing the value in the height field (everything is automatically recomputed).
2) Pre-amps cannot be simply "turned off". If you disconnect the power supply (or unplug it), but leave the pre-amp inline, then the amp becomes a dead circuit that doesn't allow anything though. An unpowered pre-amp does NOT act like a "pass thru" device. You must physically remove the amp in order to test the antenna by itself.
3) Have you tried turning the antenna in a few different directions? By experimenting with antenna aim, you might be able to find a better "sweet spot" that picks up a cleaner signal on more of the channels.