Wrong Release Code (Does not exist on system) appears in PO Release Strategy

Dear All,

I am working on a project where there is a PO release strategy that depends on the PO net value and the Release Group.
But At a certain release Strategy, a release Code appears that does not exist on the system or in the Data base Table

Ex: Rel. Grp    Rel. Strategy

         10               32

Characteristics: PO net value > 5000$

                        PGrp = ADP

only one level of approval with release Code AM: Admin Office Manager

but when the PO created, a release code AA appeared which does not exist on the system or in any data base table.

I have checked these tables T16FK, T16FV, T16FS, T16FC and T16FG and the release code does not exist. This issue only appears on the PRD server and it is working fine on DEV and QAS

Thanks in Advance.