ORA-38029: object statistics are locked

SQL> CREATE INDEX NI_ACSUM_2 ON ACD_ACC_EVENT_SUMMARIZED
ORA-38029: object statistics are locked

SQL> select owner from all_objects where object_name like 'ACD_ACC_EVENT_SUMMARIZED' and object_type = 'TABLE';
SQL> select stattype_locked from dba_tab_statistics where table_name = 'ACD_ACC_EVENT_SUMMARIZED' and owner = 'CBILLLAB_ITG';
SQL> exec dbms_stats.unlock_table_stats('CBILLLAB_ITG', 'ACD_ACC_EVENT_SUMMARIZED');