Hello Adolfo,
Implement your logic in user exit SDVFX008 (EXIT_SAPLV60B_008).
You have implemented your logic in SDVFX002 as I assume the user exits are called in sequence from *002 to *008, xaccit-kdauf might be refreshed in between this. So implement your logic at the last user exit in sequence which is SDVFX008 (EXIT_SAPLV60B_008).
Regards,
TP