backup cam reverse wire

Hello,

-I'd like to ask for help with the installation of my single din pop-out gps/radio/back-up camera head unit: eonon 1025u

I think I've completed the installation correctly but there's one problem:

*the backup camera mode is always on with just a blue screen.  Me putting it in reverse does make the view switch to the actual camera view, however, the camera mode always being on is bad because I can't enter into the gps or radio mode of the head unit.

I've wired the head unit's "reverse gear" wire into the backup fuse and directly into reverse light harness (green wire). Neither work.

If I ground the head unit's "reverse gear" wire I mysteriously still have the same occurance: camera mode always on

any suggestions?

Thank you