Please, could any one tell me what is wrong with this DB?

I tryied to run this:
GBAK -G -B -V LAMIDADOS.FDB LAMIDADOS.FDK -user SYSDBA -password masterkey

Got this:
gbak: ERROR: message length error (encountered 68, expected 52)
gbak: ERROR: gds_$receive failed
gbak: Exiting before completion due to errors