Hi Gilson,
thanks for the backup log file.
Can you please run a backup with BR_TRACE 15 and upload that log file once again. It seems like SAP uses backup_root_dir only as a backup location in your scenario and generates the RMAN command file with the usual "$SAPDATA_HOME/sapbackup" path (e.g. the generated control file copy).
Your BR*Tools are also very old (7.20 PL 8 from 2010-10-06) - PL 33 is the current one, but we should get the root cause for that wrong command file generation / the issue first.
You can also try to verify the registered data file copies with that query:
shell> sqlplus / as sysdba SQL> select NAME from V$DATAFILE_COPY;
Regards
Stefan
P.S.: I know why i don't like the BR*Tools for backup and recovery ... Native RMAN is much more straight forward without all of that unnecessary "under-the-hood" stuff :-))