SQL & PL/SQL

Oracle v10

Here's an example of a query and the output

SELECT ID, SAMPLEID, COMPOUNDNAME, REQUISITION, SUBSTR(REQUISITION,2,4) FROM SEARCH PL1 WHERE SAMPLEID = 'IA 0005 0166';

86907	IA 0005 0166	IA 0005	R2004:001160	2004
98158	IA 0005 0166	IA 0005	R2005:000956	2005

I am attempting to only return the newest row of data, in this case the 2005 row.

I tried

SELECT ID, SAMPLEID, COMPOUNDNAME, REQUISITION, SUBSTR(REQUISITION,2,4) FROM SEARCH PL1 
WHERE SAMPLEID = 'IA 0005 0166' AND
REQUISITION IN 
(SELECT MAX(SUBSTR(REQUISITION,2,4)) FROM SEARCH PL2 
WHERE SUBSTR(PL2.REQUISITION,2,4) = SUBSTR(PL1.REQUISITION,2,4));

But it returns no results. I feel I am missing something simple.

TIA