Hey guys, below is my current design:

Green section is a View Form, Pink section is a Gallery, Blue section is a New Form.
Green Section is attached to data source 1.
Pink and Blue section is attached to data source 2
I have a lookup field in data source 2 that links to the ID of items in data source 1
Essentially, the blue and pink section works as a comment system and these 'comments' are stored in a separate list but referenced via the ID of the item from data source 1.
The send icon will submit the form in the blue section. I am trying to set the default selected item for the blue section to be the ID from the green section however cant seem to get it to work.
I tried the following:
on the Default Selected Item property = [DataCardValue14.Text]
or [Text(DataCardValue14)]
with DataCardValue14 being the label that shows the ID for the green section (however I have set the visible property to false)
This wont register as a value when submitted to the list?

Could I please have some help? Im not sure why it isnt working.
Cheers, Amber