Where do you have the antenna mounted? How far away is it from the rcvr?
The pre-amp is used to get the signal from the antenna to the rcvr. It won't make the antenna receive better, just get that signal through the coax cable to the rcvr. The signal level drops quite a bit thru coax runs for upper UHF frequencies. The pre-amp boosts the received signal level from the outside part of the preamp to the inside part of the preamp. If the antenna will not receive enough signal, a preamp will not help. If the antenna receives enough, but it is lost in the coax run a good preamp will help. The RS preamps put so much noise on the line that they do not help very much. The CM preamps are able to get the signal in to the rcvr.
I found this out by taking the rcvr out to the antenna. At the antenna, I was able to receive everything very well. Inside I was not. This told me that the antenna was working fine. I connected the RS preamp, which I already had. It did not help. I replaced the coax between the antenna and the rcvr. It did not help. When I used the CM preamp everything came through very well. I added a rotator, because with a directional antenna I had to go outside and rotate it to two or three positions depending on which group of stations I wanted to watch.
EDIT: I posted this before I saw that you ordered the 4228 and 7777. It still is a pretty good way to see where your problem is. Good Luck.