Index length did not match values
Following behaviour:

``` python
import pandas as pd
# version '0.12.0'
!wget -O 'Vertikale_Netzlast_2013.csv' 'http://www.50hertz.com/transmission/files/sync/Netzkennzahlen/Netzlast/ArchivCSV/Vertikale_Netzlast_2013.csv'
df = pd.read_csv('Vertikale_Netzlast_2013.csv', header=6, sep=';', parse_dates=[[0, 1]], index_col=0, na_values=['n.v.'])
df.rename(columns={'Unnamed: 3': 'Load'}, inplace=True)
df.Load = df.Load.interpolate()
df.count
```

shows me, that everything is pretty ok:

``` python
<bound method DataFrame.count of <class 'pandas.core.frame.DataFrame'>
DatetimeIndex: 35044 entries, 2013-01-01 00:00:00 to 2013-12-31 23:45:00
Data columns (total 2 columns):
bis     35044  non-null values
Load    35044  non-null values
dtypes: float64(1), object(1)>
```

But when I try to plot it with `df.Load.plot()` I get the error message:

``` python
---------------------------------------------------------------------------
AssertionError                            Traceback (most recent call last)
<ipython-input-431-abfff097d131> in <module>()
----> 1 df.Load.plot()

/Library/Python/2.7/site-packages/pandas/tools/plotting.pyc in plot_series(series, label, kind, use_index, rot, xticks, yticks, xlim, ylim, ax, style, grid, legend, logx, logy, secondary_y, **kwds)
   1728                      secondary_y=secondary_y, **kwds)
   1729 
-> 1730     plot_obj.generate()
   1731     plot_obj.draw()
   1732 

/Library/Python/2.7/site-packages/pandas/tools/plotting.pyc in generate(self)
    854         self._compute_plot_data()
    855         self._setup_subplots()
--> 856         self._make_plot()
    857         self._post_plot_logic()
    858         self._adorn_subplots()

/Library/Python/2.7/site-packages/pandas/tools/plotting.pyc in _make_plot(self)
   1242             lines = []
   1243             labels = []
-> 1244             x = self._get_xticks(convert_period=True)
   1245 
   1246             plotf = self._get_plot_function()

/Library/Python/2.7/site-packages/pandas/tools/plotting.pyc in _get_xticks(self, convert_period)
   1032                 x = index._mpl_repr()
   1033             elif is_datetype:
-> 1034                 self.data = self.data.reindex(index=index.order())
   1035                 x = self.data.index._mpl_repr()
   1036             else:

/Library/Python/2.7/site-packages/pandas/core/series.pyc in reindex(self, index, method, level, fill_value, limit, copy, takeable)
   2644 
   2645         # GH4246 (dispatch to a common method with frame to handle possibly duplicate index)
-> 2646         return self._reindex_with_indexers(new_index, indexer, copy=copy, fill_value=fill_value)
   2647 
   2648     def _reindex_with_indexers(self, index, indexer, copy, fill_value):

/Library/Python/2.7/site-packages/pandas/core/series.pyc in _reindex_with_indexers(self, index, indexer, copy, fill_value)
   2648     def _reindex_with_indexers(self, index, indexer, copy, fill_value):
   2649         new_values = com.take_1d(self.values, indexer, fill_value=fill_value)
-> 2650         return Series(new_values, index=index, name=self.name)
   2651 
   2652     def reindex_axis(self, labels, axis=0, **kwargs):

/Library/Python/2.7/site-packages/pandas/core/series.pyc in __new__(cls, data, index, dtype, name, copy)
    490         else:
    491             subarr = subarr.view(Series)
--> 492         subarr.index = index
    493         subarr.name = name
    494 

/Library/Python/2.7/site-packages/pandas/lib.so in pandas.lib.SeriesIndex.__set__ (pandas/lib.c:29541)()

AssertionError: Index length did not match values
```

But index as well as `Load` got 35044. Bug?
