I don't know BP's but i do know electronics and I'm going to second the above posts in suggesting that the scale is off. Some need to go through a calibration before using, some are especially sensitive to the surface they are sitting on, and some are just defective.
Seems like a lot of folks get very tied up with weight. I suppose it can be important when breeding, but (and correct me if I'm wrong) if your talking about a non breeding pet I feel like if it moves well, eats, sheds, poops, and is round, you're pretty much good.