dead in the first step when train

[kingrain213]

when I tried "python train_nasnet_mobile.py", it failed as follows:
Epoch 1/20
2018-03-22 21:01:16.558680: I tensorflow/core/common_runtime/gpu/gpu_device.cc:1120] Creating TensorFlow device (/device:GPU:0) -> (device: 0, name: Tesla P40, pci bus id: 0000:83:00.0, compute capability: 6.1)
Exception in thread Thread-2:
Traceback (most recent call last):
File "software/python/lib/python2.7/threading.py", line 808, in __bootstrap_inner
self.run()
File "software/python/lib/python2.7/threading.py", line 761, in run
self.__target(*self.__args, **self.__kwargs)
File "software/python/lib/python2.7/site-packages/keras/utils/data_utils.py", line 630, in data_generator_task
generator_output = next(self._generator)
File "prj/NIMA/neural-image-assessment/utils/data_loader.py", line 100, in train_generator
train_dataset = tf.data.Dataset().from_tensor_slices((train_image_paths, train_scores))

TypeError: Can't instantiate abstract class Dataset with abstract methods _as_variant_tensor, output_shapes, output_types

Traceback (most recent call last):
File "train_nasnet_mobile.py", line 94, in
validation_steps=(5000. // batchsize))
File "software/python/lib/python2.7/site-packages/keras/legacy/interfaces.py", line 87, in wrapper
return func(*args, **kwargs)
File "software/python/lib/python2.7/site-packages/keras/engine/training.py", line 2083, in fit_generator
generator_output = next(output_generator)
StopIteration