Unique Index Type takes into consideration of deleted records.
Below is a program that will duplcate this problem. What happens is if you have duplcated records that are deleted, as in this example, when you order the table by the index, you will not see any records pertaining to these records. This is due to FoxPro, even with SET STEP ON, takes these deleted records as if they were not deleted.

** Test program for UNIQUE Index problem
CLOSE TABLES ALL
CLEAR ALL
SET DELETED ON 


IF FILE('UNQTBL.DBF')
	DELETE FILE UNQTBL.DBF
ENDIF


CREATE TABLE UNQTBL (TRMCODE C(4), COURSE C(7), SECTION C(2))

INSERT INTO UNQTBL VALUES ('1234', 'ACC101', '01') 
INSERT INTO UNQTBL VALUES ('1234', 'ACC101', '01')
INSERT INTO UNQTBL VALUES ('1234', 'ACC101', '01')

&& This will delete the first two identical records and leave 
&& the last record visible.
GO TOP
DELETE
SKIP 
DELETE 

INDEX ON TRMCODE + COURSE + SECTION TAG UNIQREC UNIQUE
&& Actual results show no records due to the prior deleted duplicate data
BROWSE