Can't add fkey in browser20

I have been unable to define a relationship in the schema editor of Oracle browser. The error message is BRW-15380: Foreign key must reference primary or unique key.

The referenced column is a primary key - it is shown in bold. Adding a NOT NULL constraint did not help. The same error is indicated whether using ctrl-MS1 or the Define Relationship dialog to try to add the foreign key.

The relationship can be added using SQL*Plus and then shows up after restarting the schema editor. EDIT_SCHEMA has been enabled in BROWSER_PROFILE. Versions are

    Oracle Browser - Extended Edition, 2.0.9.2.5 Production     Oracle Server 7.3.2
    AIX 4.1.4

-- 
Pete Forman
Western Geophysical
pete.forman_at_bedford.waii.com