Trees have a significant impact on TV signal so that's problem #1. You don't say how far you are from a source for TV.
Assuming you have a Winegard Batwing antenna, then you have a booster already in the head of the antenna and the green light indicates that power is going to the booster. If the antenna head does not have the Winegard Wingman add on component, you might try adding one assuming it will fit. Sometimes where the antenna is installed prevents the Wingman from being added due to other items on the roof interfering.
Did you try rotating the antenna in 90 degree increments and rescanning? digital signals are very directional and sometimes you have to almost be pointing dead at the station to get a good signal.
Winegard sells a replacement for the base power/booster switch that is supposed to further boost the signal. I have no experience with it.
You may want to check all of the external coax connections to assure they are corrosion free and secure.