There are several reasons for this exception. Do either of these apply to your case:
- There is a composite-id involved in one of the mappings, but the method named method returns an object of the wrong class (e.g. it should return a CompanyLocationID class, but is returning an Integer).
- The getCid() method and cid id have different types (int vs. String, etc.)
There are other ways that this can happen, but I can't recall them off-hand. Post again with more details, larger mapping posts (ids are vital), and, of course, code tags.