T5model result get <UNK>
### Model description

config = T5Config(num_layers=12,
                      num_decoder_layers=12,
                      pad_token_id=0,
                      es_token_id=VOCAB_SIZE + 2,
                      model_parallel=True,
                      vocab_size=VOCAB_SIZE,
                      num_heads=12,
                      d_model=1024,
                      d_kv=64,
                      d_ff=3072,
                      decoder_start_token_id= VOCAB_SIZE_ZH + 1,
                      )
model = T5ForConditionalGeneration(config)
this is my T5 model config.
 epoch is 200 .I use it to train a translation model, but the result is <UNK>.
How can I use T5ForConditionalGeneration to train my custom model?
my config is right?

### Open source status

- [ ] The model implementation is available
- [ ] The model weights are available

### Provide useful links for the implementation

_No response_