Xantech and Theta Dreadnaught

Anyone use the Xantech 599-00 pulsed switch to convert from steady voltage to a pulse for standby and surround triggering?

I've followed the schematic Xantech provides to perform this function but I'm not having any luck.

I have more than one 599-00 so I know it's not bad and I can trick the amp with a short voltage so I know it's not the issue. And I do have the required diodes going the right way round. :-)

If you've done this successfully, I'd love to hear about it!

Regards,
Craig