Creating a Directory

Hi,

I'm reading this:

Managing Disk Group Directories

https://docs.oracle.com/database/121/OSTMG/GUID-F7DDEB35-2BD9-467B-ADAE-89C9A8993DCA.htm#OSTMG10063

And I see:

Assuming no subdirectory exists under the directory +data/orcl, the SQL statement fails in Example 5-11.

Example 5-11 Creating a new subdirectory

ALTER DISKGROUP data ADD DIRECTORY '+data/orcl/first_dir/second_dir'; 

I can not understand why?
Should we first create first_dir and then second_dir?

In two steps:
1:
ALTER DISKGROUP data ADD DIRECTORY '+data/orcl/first_dir'; 
2:
ALTER DISKGROUP data ADD DIRECTORY '+data/orcl/first_dir/second_dir';