title: ValueError: Cannot set a frame with no defined index and a value that cannot be converted to a Series
body: <p>I'm using Pandas 0.20.3 in my python 3.X. I want to add one column in a pandas data frame from another pandas data frame. Both the data frame contains 51 rows. So I used following code:</p>
  
  <pre><code>class_df['phone']=group['phone'].values
  </code></pre>
  
  <p>I got following error message:</p>
  
  <pre><code>ValueError: Cannot set a frame with no defined index and a value that cannot be converted to a Series
  </code></pre>
  
  <p>class_df.dtypes gives me:</p>
  
  <pre><code>Group_ID         object
  YEAR             object
  Terget           object
  phone            object
  age              object
  </code></pre>
  
  <p>and <code>type(group['phone'])</code> returns <code>pandas.core.series.Series</code></p>
  
  <p>Can you suggest me what changes I need to do to remove this error?</p>
  
  <p>The first 5 rows of group['phone'] are given below:</p>
  
  <pre><code>0    [735015372, 72151508105, 7217511580, 721150431...
  1                                                   []
  2    [735152771, 7351515043, 7115380870, 7115427...
  3    [7111332015, 73140214, 737443075, 7110815115...
  4    [718218718, 718221342, 73551401, 71811507...
  Name: phoen, dtype: object
  </code></pre>