Can't add a LSTM layer to model

Question

I'm using python 3.5, and here are some packages that are installed:

• Keras 2.0
• TensorFlow 0.12.1
• Theano 0.8.2

Here is my code:

from keras.models import Sequential
from keras.layers import LSTM

model = Sequential()
model.add(LSTM(512, input_shape=(36, 45), return_sequences=True))

and here is error message:

TypeError: Expected int32, got list containing Tensors of type '_Message' instead.