Getting "Left side of [.thing] must be a STRUCTURE type" in nested structures

Hi guys, I'm back doing a little side-hustle AV programming job. I've had to re- set up my environment: Win7 Enterprise 32bit running in VMWare on a Mac, fresh download of Netlinx Studio 4.4.1626, compiler 2.5.2.420

I copied a file I had compiled and running on a controller, modified it for my new current project, but got a compile error the first time it ran into a nested structure call: rm[this_rm].d[this_did].name it puked up this compile error.

I've got the structure for "d" defined before the structure for "rm".

Can this be caused by an errant square bracket somewhere else in the code? I can't figure out why I'm getting this error, except this is the first time I've compiled this code in NS 4, the last time I worked on this code base I was still running NS 3.

Thanks for any help or suggestions,