Pie chart in https://plot.ly/pandas/pie-charts/ doesn't work

Hi, unexpected error when I put the following code copied exactly from https://plot.ly/pandas/pie-charts/in jupyter notebook

Blockquote
import cufflinks as cf
import pandas as pd

cf.set_config_file(world_readable=True,offline=False)
pie=cf.datagen.pie()
print pie.head()
pie.iplot(kind=‘pie’,labels=‘labels’,values=‘values’)

Blockquote

Error code:
The data property of a figure may only be assigned a list or tuple that contains a permutation of a subset of itself Received element value of type <type ‘dict’>