indexing
``` python
import pandas as pd
from numpy.random import rand
idx = pd.date_range(start='5/20/2013', end='5/21/2013')
df = pd.DataFrame({k:(100*rand(len(idx))).astype('int') for k in ['6', '36']}, index=idx)
```

everything looks fine:

``` python
>>> df
            36   6
2013-05-20  58  23
2013-05-21  68  31
```

and even this works:

``` python
>>> df['6']
2013-05-20    23
2013-05-21    31
Freq: D, Name: 6, dtype: int32
```

but this is one fails:

``` python
>>> df['36']
Empty DataFrame
Columns: [36, 6]
Index: []
```

it seems to me the problem comes from a 'DatetimeIndex', because this works fine:

``` python
>>> df.index = [d.date() for d in df.index]
>>> df['36']
2013-05-20    58
2013-05-21    68
Name: 36, dtype: int32
```
