OFR Extract Learnset issues

Hi
I am working on a POC to get OFR to extract data from scanned drawings. This is not related to AP, so I have had to start from scratch with a lot of things.
I've been working through the "OFR Designer Guide", but I have hit a couple of issues that have stopped me in my tracks.

Here's what I do have:
- I have created a Classification Learnset and OFR is now classifying images correctly
- My Class structure looks like this:
    - Drawing.sdp
        - Drawing
            - Architectural
            - Engineering
            - Generic
            - Geographic
        - Map
        - Void

I am currently trying to set up the field extraction. I'm only extracting a couple of fields from the images.