[TenTec] Omni VI Keying Non-TT AMP--HELP

[Art Trampler]

Hi,
I'm at WØS a Special Event Station remembering the efforts of the Radio Officers on the Titanic 98 years ago.  See www.wzeros.com or www.titanicbranson.com.
I have my Omni VI and an AL-1500 and I can't key the amp from the rig's NO output.
I have the TX EN and TX OUT jumpered together.  Do I need to set something in the menus?  I don't have the manual with me.
Because it's time critical, my number is 417-861-7842 for a call or text message.
Thanks,Art KØRO