Talkback to Cue in Cubase 12

Talk back configured on its own channel in the Control Room (through its own channel on an interface)- working fine in that the channel is available for routing to a track if required (such as setting up/recording a ‘Count In’ track) but pressing the TB button to enable talkback routing to Cue mixes does not work.
I can do a work around by creating a separate track (source the Talkback mic) and then routing that pre-fade to the Cue but that is not what I expected. I was expecting that clicking the TB button would automatically route the Talkback signal to the Cue send.
Where have I gone wrong?

this is a snapshot of the Control Room Set up in Audio connections

Fixed it - I was forgetting to activate the Talkback in the Control Room panel - Duh!!!