奖励模型问题

我用脚本评分后，出现的分数为零，请问这是什么情况呢？下面是我的评分代码：
import torch
from transformers import AutoModel, AutoTokenizer

model = AutoModel.from_pretrained(
"/root/autodl-tmp/xtuner/work_dirs/internlm2_chat_1_8b_reward_qlora_varlenattn_ultrafeedback_copy/iter_15230_hf",
device_map="cuda",
torch_dtype=torch.float16,
trust_remote_code=True,
)
tokenizer = AutoTokenizer.from_pretrained("/root/autodl-tmp/xtuner/work_dirs/internlm2_chat_1_8b_reward_qlora_varlenattn_ultrafeedback_copy/iter_15230_hf", trust_remote_code=True)

chat_1 = [
{"role": "user", "content": "Hello! What's your name?"},
{"role": "assistant", "content": "My name is InternLM2! A helpful AI assistant. What can I do for you?"}
]
chat_2 = [
{"role": "user", "content": "Hello! What's your name?"},
{"role": "assistant", "content": "I have no idea."}
]

# get reward score for a single chat
score1 = model.get_score(tokenizer, chat_1)
score2 = model.get_score(tokenizer, chat_2)
print("score1: ", score1)
print("score2: ", score2)
# >>> score1: 0.767578125
# >>> score2: -2.22265625

# batch inference, get multiple scores at once
scores = model.get_scores(tokenizer, [chat_1, chat_2])
print("scores: ", scores)
# >>> scores: [0.767578125, -2.22265625]

# compare whether chat_1 is better than chat_2
compare_res = model.compare(tokenizer, chat_1, chat_2)
print("compare_res: ", compare_res)
# >>> compare_res: True

# rank multiple chats, it will return the ranking index of each chat
# the chat with the highest score will have ranking index as 0
rank_res = model.rank(tokenizer, [chat_1, chat_2])
print("rank_res: ", rank_res) # lower index means higher score
# >>> rank_res: [0, 1]