Far from experianced myself but id say you dont have a great chance of him cacthing a rabbit on the lamp he will miss a lot more than he will catch, you say he goes to cover well, so hed be more likely to catch one there where its sitting in cover already, as you say he is young and still learning, but let him rag a fresh carcass that should let him know what your after, or skin a rabbit and put it over a retreiving dummy for practising with.