conditional list relationships

I've got three files: states, test, and portalTest. In states, people create a record with the name of a state and a city to go along with that. I've created a relationship between states and Test such that, when you click on the "states" field and choose a states, only the cities related to that state appear in the cities pop-up list. Great, that works just fine.

PortalTest has a relationship with Test and hopes to show its (tests) records in a portal that allows creation of records in the related file (test, in this case). However, I can't get those fields to work. The key field between PortalTest and Test is an arbitrary field called "state." I don't actually do anything with it, I just created it to define a relationship. The key between Test and states is also a field called "state", only both of those are legitimatley used in those cases. In PortalTest, when I click on the states pop-up list I do get the correct list of states. However, I get an error message reading "this field cannot be modified until 'state' is given a valid value.' I think my problem is with my key field, but I don't know what, why or how to fix it. How do I get my Test file to show up correctly in my PortalTest file? thanks ahead of time for your suggestions and expertise.