Is the insertion of the new row successful? If it is then the object that is passed to the merge call does not have a ID populated or has a new ID different from the object you expect to merge into. Note that the ID field used by TopLink is the one defined by the @ID annotation. Would it be possible for you to post the source to the entity involved in your simple test? Perhaps the test itself?
Is the row insertion failing because of a Unique Constraint violation?
--Gordon
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