NSS / backup lights question

ok so i've been rereading the posts and trying to decipher both explanations.

white wire = 12 v incoming (also read 12v on the white wire on ignition w/ voltmeter)
purple wire = sends voltage to the backup lights

the way i'm interpreting it is,

white wire is connected to one outer prong of the NSS, and the purple outgoing wire connects to the other outer prong. (haven't connected middle prong for the NSS to the starter relay ground yet.)

lights still don't go on when in reverse.

maybe i should test my lights (new bulbs, reconditioned sockets). so i connected the white and purple via a test wire, figuring that with just the ignition on, the 12v should turn on the lights. still no go.

am i doing this correctly? any thoughts?