Operation u'init_27 'is marked as unattractive. tensorflow

Question

I'm going to train my network using a keras tensorflow convolutional neural network, this is my code, I have a mistake in compiling the function, but I don’t know why

model = Sequential()  # or Graph or whatever


model.add(Embedding(input_dim = n_symbols + 1,
                    output_dim = vocab_dim,
                    input_length=maxlen,
                    dropout=0.2))

# we add a Convolution1D, which will learn nb_filter
# word group filters of size filter_length:
model.add(Convolution1D(nb_filter=nb_filter,
                        filter_length=filter_length,
                        border_mode='valid',
                        activation='relu',
                        subsample_length=1))
# we use max pooling:
model.add(GlobalMaxPooling1D())

# We add a vanilla hidden layer:
model.add(Dense(hidden_dims))
model.add(Dropout(0.2))
model.add(Activation('relu'))

# We project onto a single unit output layer, and squash it with a sigmoid:
model.add(Dense(1))
model.add(Activation('sigmoid'))

model.compile(loss='mean_squared_error',
              optimizer='adam',
              metrics=['accuracy'])
model.fit(X_train, y_train,
          batch_size=batch_size,
          nb_epoch=nb_epoch,
          validation_data=(X_test, y_test))

print("Evaluate...")
score, acc = model.evaluate(X_test, y_test,
                            batch_size=batch_size)
print('Test score:', score)
print('Test accuracy:', acc)

error:

ValueError: Operation u'init_27' has been marked as not fetchable.