Anyone got machines from UIC? I'm confused how platform validation works

[loki42]

I'm using dual lane gold feeders but when I scan the barcode it just goes blue, never gives me an error or a green validation. When I put in a feeder it pops up the right part number, and the barcode scans in the log, but they never validate. I've tried holding in the PSV tabs but I have no real idea what I'm doing... There's a flip card thing of slot / track numbers attached to the front of the machine, so maybe it's set up to use them instead of the tabs? I'm not sure  how to use them and the docs don't seem to mention that alternative way.