Update modelling_single.py

modelling_single.py

@@ -233,6 +233,7 @@ class SingleCXREncoderDecoderModel(VisionEncoderDecoderModel):
 
         if not past_key_values:
             token_type_ids = self.token_ids_to_token_type_ids(input_ids, special_token_ids)
+            decoder_inputs['past_key_values']=None  # Because at the first step, there was no past_key_values
         else:
             token_type_ids = self.token_ids_to_token_type_ids_past(input_ids, special_token_ids)