SAP HANA - cannot drop primary key of referenced table

Hello,

I am trying to execute the following query from HANA studio(HANA version 1.00.74.00.390550)

ALTER TABLE SCHEMA_NAME.MY_TABLE DROP PRIMARY KEY;

HANA issues error saying

SAP DBTech JDBC: [7] (at 23): feature not supported: cannot drop primary key of referenced table: GENERIC_OBJECT_T: line 1 col 24 (at pos 23)

Is there any permission issue? Is there any problem with the drop constraint query? Is it not possible to drop the constraint? I m trying to drop primary key because i need to add additional column to the primary key.

Thanks,

Suren.