output of generator should be a tuple (x, y, sample_weight) or (x, y)

[peach2wanzi]

The issue occured when I use Jester date set,I'm sure that the lable list is right.

Traceback (most recent call last):
File "training_res3d_clstm_mobilenet.py", line 126, in
initial_epoch=init_epoch,
File "/home/usr2/anaconda2/lib/python2.7/site-packages/tensorflow/contrib/keras/python/keras/engine/training.py", line 1857, in fit_generator
'or (x, y). Found: ' + str(generator_output))
ValueError: output of generator should be a tuple (x, y, sample_weight) or (x, y). Found: None

I am in torubled for some days,can any body help me ?Thanks so much!!!