Why are we getting error ORA-01654: unable to extend index IM_STAGE.S1REUTERS_RIC_IDX3 by 640 in ta

show parameter block_size
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_block_size                        integer     16384
SQL:sldn0977por:(EIMP1):PRIMARY> select file_name, MAXBLOCKS,AUTOEXTENSIBLE from dba_data_files where tablespace_name='STAGE_INDEX_LRG';

FILE_NAME
------------------------------------------------------------------------------------------------------------------------------------------------------
MAXBLOCKS AUT
---------- ---
/sbcdata/02/oradata/EIMP1/EIMP1_stage_index_lrg_01.dbf
        0 NO

/sbcdata/03/oradata/EIMP1/EIMP1_stage_index_lrg_02.dbf
        0 NO

/sbcdata/03/oradata/EIMP1/EIMP1_stage_index_lrg_03.dbf
        0 NO


SQL:sldn0977por:(EIMP1):PRIMARY> SELECT initial_extent,next_extent,pct_increase,extent_management, allocation_type ,segment_space_management
FROM dba_tablespaces where TABLESPACE_NAME='  2  STAGE_INDEX_LRG';

INITIAL_EXTENT NEXT_EXTENT PCT_INCREASE EXTENT_MAN ALLOCATIO SEGMEN