does anyone know how to populate a dropdown box with only items corresponding to a parameter fed into an IQA?

I have a CCO with two tabs on a page. My goal is to list items in a dropdown box that correspond to a selected eventCode.

On the second tab, I have (what the world normally calls) a dropdown box which is supposed to be powered by an IQA. The dropdown box should show the values returned by the IQA. The IQA uses the "@url:EventKey" convention to retrieve a value from the ?EventKey=EVENTCODE parameter in the querystring to "filter" the list of values only to those that match the EventKey.

What I expect to happen: When I click onto the CCO 2nd tab -- I expect to see a dropdown box populated by items returned from the results of the IQA. Specifically, I would see items like this in the dropdown box:
BOB JONES - Event W111XX0000
JOHN BOBBY - Event W111XX0000
JANE DOE - Event W111XX0000
...etc

What actually happens: When I click on the CCO 2nd tab -- I see the text of the IQA with the entire returned set of data from the IQA that shows that the IQA IS retrieving the querystring EventKey parameter. There is no dropdown box...but there IS an Edit Pencil. When I click Edit Pencil, the dropdown box appears (which is odd), but the list of items is now completely unfiltered by the querystring parameter value.
I see this when the tab originally loads which indicates the IQA DOES sense the parameter...
BOB JONES - Event W111XX0000JOHN BOBBY - Event W111XX0000JANE DOE - Event W111XX0000....etc.

I am looking into the FormFieldData and FormFieldResponseData classes which don't make a lot of normal sense to me in the terms of what I would call a DropDownBox that would expect an array or just plain old list of items in the Text and Value format.

Can someone detail to me how to produce a normal DropDown box list of selectable items in iMIS that can react to some value fed into it in any way (whether it be via hidden field, or a session variable...or (preferably) a querystring value. I need the IQA to list items in a dropDown box for selection. This would normally be a rather standard task...but is odd in my opinion the way iMIS handles this task.

NOTE: I apologize if EventKey and EventCode seemed mixed up here - but that is iMIS doing that, not me.

the documentation describes "feeding parameters in to IQA" and using the "@url:EventCode" ("@url:EventKey") convention but nothing seems to work.

If someone could explain this, it would very much this and other iMIS dropdown boxes in the future...

Jack Donahue