Signal problem. Appreciate any help

[Dukenukem]

I've recently installed a Maxx uav antenna on my P3S. I'm also using litchi app. On the top right side of the litchi app screen is two signal indicators. (Video and signal) the video signal shows 0 bars (red line) today while flying. But did show two green curved bars (green line). I successfully flew it 4000 ft away. I kept video signal the entire time. Can anyone tell me why I'm not showing signal bars? Appreciate any help.

 

[Duchunter]

I'm still trying to figure out why the signal bars are red sometimes instead of white with full signal.