title: join() returning NaN values in python
body: <p>I have some int type values in my series and I tried to join it with a data frame but the series got added as a column but the values are not as expected they are filled with 'NaN'
  this is my code</p>
  <pre><code>s3=Series(np.arange(6))
  s3.name=&quot;added_series&quot;
  np.random.seed(25)
  df=DataFrame(np.random.rand(36).reshape((6,6)),index=['r1','r2','r3','r4','r5','r6'])
  dfadd=DataFrame.join(df,s3)
  </code></pre>
  <p><img src="https://i.stack.imgur.com/60ADt.png" alt="Here is the output image" /></p>