ts.plot() pandas: No plot!

[Paulo da Silva]

Hi!

I am learning pandas and following the tutorial I tried the following:
ts = pd.Series(np.random.randn(1000), index=pd.date_range('1/1/2000',
periods=1000))
ts = ts.cumsum()
ts.plot()

No plot is produced!
Only the following output:
<matplotlib.axes.AxesSubplot object at 0x7f33019b6630>

Any clue on what is happening?

I'm using kubuntu and python3.

Thanks.
Paulo