Tensor2tensor: My customed problem never registered with registry problems - tensorflow

Question

Description
I am following a tutorial of microsoft from this website
to get a model to inference Chinese couplet.
Now I have trained the model on Google cloud and I can also get good inference.
Howerver, when I am constructing inference service, I found my function to communicate with tensorflowserverapi can't find my problem get registered.
I also have trained this model for one step and add t2t_trainer --registry_help, and I can see my problem is actually registered under problems Problems.
My code is just the same as the one in this repo script
And here is my test code:
from up2down_model.up2down_model import up2down
upper_couplet = input()
up2down.get_down_couplet([upper_couplet])
Environment information:
OS: Ubuntu 20.04
$ pip freeze | grep tensor
tensor2tensor 1.15.6
tensorboard 1.14.0
tensorflow 1.14.0
tensorflow-addons 0.10.0
tensorflow-datasets 1.3.0
tensorflow-estimator 1.14.0
tensorflow-gan 2.0.0
tensorflow-hub 0.8.0
tensorflow-metadata 0.22.0
tensorflow-probability 0.7.0
tensorflow-serving-api 1.14.0
$ python -3.7.7
Error logs:
raceback (most recent call last):
File "/home/enigma/anaconda3/envs/NLP/lib/python3.7/site-packages/tensor2tensor/utils/registry.py", line 509, in problem
return Registries.problems[spec.base_name](
File "/home/enigma/anaconda3/envs/NLP/lib/python3.7/site-packages/tensor2tensor/utils/registry.py", line 254, in __getitem__
(key, self.name, display_list_by_prefix(sorted(self), 4)))
KeyError: 'translate_up2down never registered with registry problems. Available:
All problems without my own
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "test.py", line 1, in <module>
from up2down_model.up2down_model import up2down
File "/home/enigma/Desktop/NLP/service/up2down_model/up2down_model.py", line 85, in <module>
up2down = up2down_class(FLAGS,server_address) # inference model
File "/home/enigma/Desktop/NLP/service/up2down_model/up2down_model.py", line 40, in __init__
self.problem = registry.problem(self.FLAGS.problem)
File "/home/enigma/anaconda3/envs/NLP/lib/python3.7/site-packages/tensor2tensor/utils/registry.py", line 513, in problem
return env_problem(problem_name, **kwargs)
File "/home/enigma/anaconda3/envs/NLP/lib/python3.7/site-packages/tensor2tensor/utils/registry.py", line 527, in env_problem
ep_cls = Registries.env_problems[env_problem_name]
File "/home/enigma/anaconda3/envs/NLP/lib/python3.7/site-packages/tensor2tensor/utils/registry.py", line 254, in __getitem__
(key, self.name, display_list_by_prefix(sorted(self), 4)))
KeyError: 'translate_up2down never registered with registry env_problems. Available:\n reacher:\n * reacher_env_problem\n tic:\n * tic_tac_toe_env_problem'