Using a placeholder for ObjectType in attribute filter

[Derek Fields _RightStar_]

I have an objectType called "Workstation". I have a second objectType called "Equipment Type". I created an attribute on Workstation that references the Equipment Type object type. My Equipment Type object has a Category attribute that has the objectType name in it. I have several objects that have a Category of "Workstation". 

According to the documentation, this should work as an AQL filter in an object reference attribute:

Category = ${objectType}

I should be able to see just the Equipment Type objects that have Category = Workstation. In fact, if I replace the AQL filter with

Category = Workstation

it works as expected. I suspect that objectType is either not returning anything or is returning something different from Workstation.

Any suggestions on how to make this work?