Try plugging in the USB power for the antenna into a separate power source such as a 2 amp cell phone charger.
Just a guess, there could be a chance the hopper does not have enough power on the USB port to power the dongle and antenna. Antenna could be sucking all the power to the point the dongle cannot operate.
Stick a paper clip in the dongle to act as an antenna, and only connect the dongle to the hopper. Depending on the area you may pick up a few channels using this method and this will help you trouble shoot the situation.
Its also possible that the amplifier is introducing too much noise into the signal from the antenna. To be perfectly honest with you the antenna you have is crap, but may work good depending on how close you are to the broadcast towers. Ever since broadcasts went digital, its a known fact that all tuners in TVs and devices such as the Hopper USB dongle have different sensitivity levels when picking up over the air signals.
If anyone remembers the DTV pal, there was 2 different versions of that set top box. The second version or generation of the DTV pal had a better tuner which had the ability to pick up more stations. Its almost like the fact your TV picks up lots of channels. However you should get something on the dongle, the fact you get nothing means you got something going on such as the power.
I think its really crappy that in an effort to save money a lot of these companies are not including USB power adaptors. I get it, but a lot of people do not have good charging devices, For example, I have several google nest cameras A few of my cameras are outdoor and the USB power supply got wet and damaged.
I had a cheap 1 amp charger sitting in my kitchen drawer and used that. Camera lit up but would not work. I had to get a 2 amp charger off amazon the other day to make it work again.
Even though my nest camera came with a charger, point was not everyone is going to have a spare charger laying around that can provide power a device correctly, especially when none of these devices that likely came from China state the power requirements on them