Keras extention problem

Hi all,

I installed rapidminer in Ubuntu 14. I test python scripting and keras in rapidminer and it say python 3.4.3 is detected (as expected). 

Then, I run the examples of keras extension. The script stoped abnormally, the log message is as below:

It seems tha the problem is that graphviz and pydot cannot be imported. However, I tried to import both of them in python and successeeded 

Dec 8, 2017 4:00:14 PM INFO:
Dec 8, 2017 4:00:14 PM INFO: 32/135 [======>.......................] - ETA: 0s - loss: 0.5211
Dec 8, 2017 4:00:14 PM INFO: 135/135 [==============================] - 0s - loss: 0.6655
Dec 8, 2017 4:00:14 PM INFO: Epoch 127/128
Dec 8, 2017 4:00:14 PM INFO:
Dec 8, 2017 4:00:14 PM INFO: 32/135 [======>.......................] - ETA: 0s - loss: 0.5119
Dec 8, 2017 4:00:14 PM INFO: 135/135 [==============================] - 0s - loss: 0.6613
Dec 8, 2017 4:00:14 PM INFO: Epoch 128/128
Dec 8, 2017 4:00:14 PM INFO:
Dec 8, 2017 4:00:14 PM INFO: 32/135 [======>.......................] - ETA: 0s - loss: 0.5030
Dec 8, 2017 4:00:14 PM INFO: 135/135 [==============================] - 0s - loss: 0.6572
Dec 8, 2017 4:00:14 PM INFO: Couldn't import graphviz or pydot. Model will not be visualised.
Dec 8, 2017 4:00:15 PM SEVERE: Process failed: Script terminated abnormally.
Dec 8, 2017 4:00:15 PM SEVERE: Here:
Dec 8, 2017 4:00:15 PM SEVERE: Process[1] (Process)
Dec 8, 2017 4:00:15 PM SEVERE: subprocess 'Main Process'
Dec 8, 2017 4:00:15 PM SEVERE: +- Retrieve Iris[1] (Retrieve)
Dec 8, 2017 4:00:15 PM SEVERE: +- Split Data[1] (Split Data)
Dec 8, 2017 4:00:15 PM SEVERE: +- Keras Model[1] (Keras Model)
Dec 8, 2017 4:00:15 PM SEVERE: subprocess 'Executed Process'
Dec 8, 2017 4:00:15 PM SEVERE: | +- Add Core Layer[1] (Add Core Layer)
Dec 8, 2017 4:00:15 PM SEVERE: ==> | +- Add Core Layer (2)[1] (Add Core Layer)
Dec 8, 2017 4:00:15 PM SEVERE: +- Apply Keras Model[0] (Apply Keras Model)