我編寫了類似于此代碼的架構： https ://keras.io/guides/function_api/#manipulate-complex-graph-topologie ：visual_features_input = keras.Input(    shape=(1000,), name="Visual-Input-FM", dtype='float')   et_features_input = keras.Input(      shape=(12,), name="ET-input", dtype='float')   sentence_encoding_input = keras.Input(    shape=(784,), name="Sentence-Input-Encoding", dtype='float')       et_features = layers.Dense(units = 12, name = 'et_features')(et_features_input)  visual_features = layers.Dense(units = 100, name = 'visual_features')(visual_features_input)  sentence_features = layers.Dense(units = 60, name = 'sentence_features')(sentence_encoding_input)  x = layers.concatenate([sentence_features, visual_features, et_features], name = 'hybrid-concatenation')  score_pred = layers.Dense(units = 1, name = "score")(x)  group_pred = layers.Dense(units = 5, name="group")(x)    # Instantiate an end-to-end model predicting both score and group  hybrid_model = keras.Model(      inputs=[sentence_features, visual_features, et_features],      outputs=[group_pred]      # outputs=[group_pred, score_pred],  )但我收到錯誤：ValueError: Graph disconnected: cannot obtain value for tensor Tensor("Sentence-Input-Encoding_2:0", shape=(None, 784), dtype=float32) at layer "sentence_features". The following previous layers were accessed without issue: []知道為什么嗎？