[Elecraft] N8LP Tuning Relay w/ K3/KPA500 - help, please

[Hunsdon Cary III]

Elecraft Reflector participants:
If any of y’all use the N8LP tuning relay w/ your K3 and KPA500, I appreciate your help.
My kit went together smoothly and all ohm meter checks A-OK. When I plug the relay into the SteppIR control box the green light comes on.
I have RCA phono plug cable running from the PTT connection on the relay to the PTT In connector on K3 and another from the PA Key on Amp to the LOOP plug on Relay box.
When I key PTT while SteppIR is tuning, KPA500 does not switch to standby as I believe it should.
Obviously I’m doing something wrong.  I even tried the Key Out connection on the K3 but that didn’t work either.
Any thoughts would be appreciated!
73,
Cary, K4TM
Lynchburg VA
H. Cary III
h3cary at gmail.com