Failed to get information in bdm and used it in operations.

Hi,

I am getting the max value of a certain column in bdm table using custom query with parameter. Then I call the query using DAO and used it in the operations once the manager have approved the task. But when i run the task it always fails. I set the petCashNo to store a new series of pet cash no. Just want to create a petcash series number

This is my custom query

SELECT MAX(p.petCashNo)
FROM PettyCashHeader p
WHERE p.branch = :branch

Return of custom query is single

This is how i call my query in operations

pettyCashHeaderDAO.findByMaxPetCashNo(branch)

The branch parameter is defined in the local variables

pettyCashRequest.getBranch()

Please help. Thanks very much