Relay Test Fail, technical help please

Hello,
I’ve wired my Castle Euro Mini (7 of 10 zones in use) to 2 interface boards + Panel PRO.
I can do everything (zones, PGMs) apart from the relay.
When I connect relay to Zone 8 & COM, it always fails the test on that zone when I come out of engineering mode.
I’m lost, as I’ve set to Keyswitch, Normally On = No.
And I’ve used Gemini to help talk me through troubleshooting, but have got stuck.

Can anyone point me in the right direction, please? I’m tantalisingly close!

Thank you!

Walders

Possibly need a resistor on that keyswitch zone in the normal state. Does the manual say anything about that?