title: Can't convert dates to datetime64
body: <p>The following piece of code:</p>
  
  <pre><code>import pandas as pd
  import numpy as np
  
  data = pd.DataFrame({'date': ('13/02/2012', '14/02/2012')})
  data['date'] = data['date'].astype('datetime64')
  </code></pre>
  
  <p>works fine on one machine (windows) and doesn't work on another (linux). Both numpy and pandas are installed on both. </p>
  
  <p>The error I get is:</p>
  
  <pre><code>ValueError: Cannot create a NumPy datetime other than NaT with generic units
  </code></pre>
  
  <p>What does this error mean? I see it for the first time ever and there is not much on the web I can find. Is it some missing dependency? </p>