Pandas graphing time series issue
```

import pandas as pd
import numpy as np
import matplotlib
import matplotlib.pyplot as plt
%matplotlib qt


exampl = [4.4,5.1,6.1,6.2,6.1,6.1,5.7,5.2,4.7,4.1,3.9,3.5]
dates = pd.date_range('2016/10/29 5:30pm', periods = 12, freq='H')

series = pd.Series(exampl, dates)


series15m = series.resample('15min').interpolate(method = 'cubic')

series15m.plot()
series.plot()
plt.legend()
plt.show()
```

#### Problem description

I tried this code and the graph it ends up is messed up, I figured it was matplotlib and I asked them for help and the lead developer told me it probably wasn't matplotlib.


![helppanda](https://user-images.githubusercontent.com/15021936/52758694-41355880-2fd7-11e9-80f4-c83dad6fa938.PNG)
