problem with creating non default blocksize tablespace

I've already set the db_2k_cache_size
is there a limitation for setting this up. what do i need to check .
what am i doing wrong.
couldnt find anything on metalink nor the docs.      

SQL> CREATE TABLESPACE D_PATLOB DATAFILE
'/dev/rvd_bptrnext8' SIZE 20010M AUTOEXTEND OFF,
'/dev/rvd_txnrsp3' SIZE 9000M AUTOEXTEND OFF
LOGGING
ONLINE
PERMANENT
EXTENT MANAGEMENT LOCAL UNIFORM SIZE 200M BLOCKSIZE 2K;
  2 3 4 5 6 7 8 CREATE TABLESPACE D_PATLOB DATAFILE *
ERROR at line 1:
ORA-01144: File size (10245120 blocks) exceeds maximum of 4194303 blocks  

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