SQL & PL/SQL

I can't figure out what is wrong with my SQL here:

pstmt60RemEmail=conEZ.prepareStatement(
"select sude.OPE_ID as OPE_ID, sude.YEAR as YEAR, sude.DUE_DATE as DUE_DATE, "
+ "sude.FYE as FYE, i.TYPE as INST_TYPE "
+ "from SUBMISSION_DETAIL sude, INSTITUTION i "
+ "where (sude.OPE_ID, sude.YEAR) in ( "
+ "select sd.OPE_ID as OPE_ID, sd.YEAR as YEAR "
+ "from SUBMISSION_DETAIL sd "
+ "where (sd.FS_FLAG = 'N' or sd.CA_FLAG = 'N') "
+ "and sd.DUE_DATE <= (sysdate+60) and sd.DUE_DATE > (sysdate+30);"
);

The SQL works fine in TOAD but when I execute it via my .java, I get ORA-00920: invalid relational operator

Any clues?

Thanks
-Dhaval