compress partitioned index gets error ORA-28659

 Hi  Everyone,
I get error ORA-28659 when issuing this command:
alter index IX_ORDER_MED_CSN_INST rebuild partition P1 compress;
ORA-28659: COMPRESS must be specified at object level first

so I run (as suggested from the error code)
ALTER table order_med MODIFY DEFAULT ATTRIBUTES COMPRESS;
table altered;
come back to re-run:
alter index IX_ORDER_MED_CSN_INST rebuild partition P1 compress;
still get
ORA-28659: COMPRESS must be specified at object level first.

thought that I need to work at index object level, I run:
alter index IX_ORDER_MED_CSN_INST rebuild compress;
ORA-14086: a partitioned index may not be rebuilt as a whole,