From RDS AWS, I am not able to restore a database header only from S3 bucket:

RESTORE HEADERONLY  FROM  DISK  = N'arn:aws:s3::myBucket/myDB.bak'

Just to check access, I can restore the full database without errors :

exec msdb.dbo.rds_restore_database 
@restore_db_name='myDBName', 
@s3_arn_to_restore_from='arn:aws:s3::myBucket/myDB.bak'

Is this even possible? what am I missing? Why restore header only is not working ? Any other alternatives ?