Server Administration :: Table Cannot Shrink?

My table can not shrink, why?

SQL> Alter Table tb_hxl_user Shrink Space Cascade;
Alter Table tb_hxl_user Shrink Space Cascade
*
ERROR at line 1:
ORA-10635: Invalid segment or tablespace type

SQL> desc tb_hxl_user;
Name Null? Type
----------------------------------------- -------- ----------------------------
STATEDATE NOT NULL DATE
USERNUMBER NOT NULL VARCHAR2(13)
PROVCODE NOT NULL NUMBER

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