Numeric Concatenation Failure On 4 Fields

I have a table:
batch_date numeric (8,0)
batch_nmbr numeric (5,0)
batch_ctr numeric (4,0)
col4...
col5...
col6...

I am trying to select data using something like:
select col1, col2
FROM
tablename
WHERE
(BATCH_DATE +
BATCH_NMBR +
BATCH_CTR) >= (:BATCH-DATE
+ :BATCH-NMBR
+ :BATCH-CTR)

this is a mssql cursor embedded in a microfocus cobol program.

I do not get predictable results.