The database server cannot locate the referenced constraint in the sysconstraints system catalog table, and the referenced constraint was not created in the same ALTER TABLE statement as the referencing constraint. The referenced constraint might not exist, or a foreign key might refer to a table that has a unique constraint but not a primary-key constraint.

Check that you have entered a valid column name with the appropriate constraints that are associated with it. If the referenced table has a unique constraint but no primary key, you must use the following form of the REFERENCES clause:

REFERENCES table_name (column_name)

Valid constraint columns indicate an internal error. If the error recurs, note all circumstances and contact IBM Informix Technical Support.