PROCEDURE combo1.Valid LOCAL lcFilter SELECT < Table used to populate RowSource of List Box > lcFilter = [ < field in List Box Cursor that defines the filter > ] + TRANSFORM( this.Value ) SET FILTER TO &lcFilter GO TOP Thisform.List1.Requery() ENDPROCI am guessing that the reason you are getting the error you describe is that you are trying to set the filter using this (incorrect) syntax:
SET FILTER TO < Field in List Box Cursor > = This.Value