Input Control w/Query Results

I'm trying to use query results to retrieve a list of departments from a database, then have those departments appear in a multi-select input control.  For the longest time I was getting "(NULL)" for every department in the query, and selecting one of the null results would run the report as if I had selected an actual department.  If the department name itself is the first visible query column, I receive a list of null results, but if I use a column which returns integers as the first visible column and the department name column as the second visible column, suddenly the list returns integers followed by department names ("01 | 01 - Grocery").  I'd like to be able to show only department names without first displaying a number, but I can't seem to figure it out.  I'm getting the feeling it has something to do with data types, but I don't know enough to pinpoint the problem.  The parameter class I'm using is java.util.collection if that helps at all.  Thanks!