SM9.4 - how to pull a variable from a join?

I have data for my CI's that is put together with a join - data from "device" table and "labcommon" table. I can see all the variables when I run "d $L.file" and the outputs starts with my join name labjoin={[{["data...." ... the issue is that when i run "d <fieldname> in $L.file" I can only get values that live in the "device" table. I input a value that lives in the "labcommon" table and it comes back as NULL, but i can see the value when i run "d $L.file"


is there a special way to get values from a join?