Adding Ref. Integrity

I am tring to add referential integrity to an already populated table. I keep getting an ORA2294 error - parent keys do not exist.

I have removed all the offending records I can find, and I still get the same problem. I have checked, and rechecked, that the parent records exist, and can find parent records for all records in the child table. I have checked that the fields have primary keys. Any ideas?

The parent table has a field, say: P_NUMBER VARCHAR2(7). This is a primary key. (There are other firlds.

The child table has several fields also. The key ones are:

	C_NUMBER  VARCHAR2(7)
	C_MONTH   VARCHAR2(4)

Its primary key is a composite key, C_NUMBER and C_MONTH.

I have checked that all values in C_NUMBER exist in P_NUMBER, and they do.

The code for the constraint is (from memory, its at work):

alter table CHILD
  add (constraint CP_NUMBER
    foreign key (C_NUMBER)
    references Parent (P_NUMBER);

Any help appreciated.

TIA.

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