parallel dml question

Hello guru's,

I am trying to execute something like

alter session enable parallel dml;

insert /*+ parallel(4) */ into core_tab ct  select * from temp;

Notes: Database version 11.2.0.3 , CORE_TAB is range partitioned and has 5 parent tables and also has a function based index on it.

question:  based on the explain plan i see that the insert is not running in parallel. then i came across the below restriction matrix in oracle docs

FOREIGN KEY (Referential Integrity)

Restrictions for referential integrity occur whenever a DML operation on one table could cause a recursive DML operation on another table. These restrictions also apply when, to perform an integrity check, it is necessary to see simultaneously all changes made to the object being modified.