database.links.ini question

Hi -- I'm experiencing a puzzling (lack of) behavior that I hope tracks to something I'm not understanding fully. I'd much appreciate someone's input. Do the fields one is linking to in the database.links.ini file need to be integers in order to work? If not, continue reading -- if so, well, then -- does anyone have a workaround suggestion? Details: I have a database.links.ini file (named with the database name, not the word "database"), and only some of the links I specify in this file are being created in my forms.When the links are *not* created, a regular text field displays instead of the drop down menu I am expecting. For instance, the text of the database.links.ini file is: [Presentations] pin_number = Attendees: pin_number session_id = Countries: country_id [Attendees] state_id = States: state_id city = Countries: country_id The only link in the file that properly creates a linked field in my table is session_id. I can link it to any of the other options that I have specified in the file, and the dropdown link menu will be created. None of the other three "work". So.. I thought perhaps that the fields needed to be a certain data type (...integer...?). I looked online and found this: "The databasename.links.ini file contains a section for each table, then the row that is linked equal to the table and row that it should locate the row from. It assumes the relationships are non-primary id to primary id, as the example below shows[...]" So the data types are as follows (taken from the dataObject classes). (I'm not showing data types of the fields I'm trying to link, because they all work when they are paired with session_id, so the problem isn't them). pin_number // string(40) not_null primary_key unique_key session_id // int(3) not_null multiple_key unsigned zerofill (This is the one that works -- the only int) state_id // string(2) not_null multiple_key city // string(40) *Note -- the reason I am trying to link "city" with country_id is that I wanted to try using a field that was not identified in any way as a key, just to see if that was where I was going wrong. It didn't work with country_id (// string(5) not_null multiple_key) either. I don't have any other int fields handy to try without regenerating the schema -- which I can't do until tomorrow. I hope my little theory is wrong -- it seems pretty limiting. Thanks in advance, s.