Creating dba directories and using the same to create datafile (ASM)

Dears,

can you let me what's wrong here.. Why the datafiles not getting created on dba directories. Its creating the datafiles in ORACLE_HOME not using diskgroup path.

SQL> create directory OBDX_DIR as '+DATA/<DB>/<PDB>/DATAFILE/';

Directory created.

SQL> create tablespace TEST datafile 'OBDX_DIR' size 1M autoextend on maxsize 2M;

Tablespace created.

SQL> select file_name from dba_data_files where tablespace_name='TEST';FILE_NAME

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/<ORACLE_HOME>/dbs/OBDX_DIR