Lines in picture....
1) check power adapter using with video
receiver, common to get poer adapter for
vcr commander mixed with one for receiver
(d9100 on receiver...bad)
2) interfering device, turn off (unplug)
all devices that are RF in nature. Unplug
all but 1 camera because other cameras if
not switching properly will also cause this
issue.
3) channel settings on receiver cameras
dont match (check instructions to find
these switches if you are unsure)
4) out of range, defective cam or defective
receiver! (try multiple cams 1 at a time,
replace receiver)