title: ValueError: Incompatible indexer with Series while adding date to Date to Data Frame
body: <p>I am new to python and I can't figure out why I get this error: ValueError: Incompatible indexer with Series.</p>
  <p>I am trying to add a date to my data frame.</p>
  <p>The date I am trying to add:</p>
  <pre><code>date = (chec[(chec['Día_Sem']=='Thursday') &amp; (chec['ID']==2011957)]['Entrada'])
  date
  </code></pre>
  <p>Date output:</p>
  <pre><code>
  56   1900-01-01 07:34:00
  Name: Entrada, dtype: datetime64[ns]
  </code></pre>
  <p>Then I try to add 'date' to my data frame using loc:</p>
  <pre><code>rep.loc[2039838,'Thursday'] = date
  rep
  </code></pre>
  <p>And I get this error:</p>
  <pre><code>---------------------------------------------------------------------------
  ValueError                                Traceback (most recent call last)
  &lt;ipython-input-347-3e0678b0fdbf&gt; in &lt;module&gt;
  ----&gt; 1 rep.loc[2039838,'Thursday'] = date
        2 rep
  
  ~/anaconda3/lib/python3.7/site-packages/pandas/core/indexing.py in __setitem__(self, key, value)
      188             key = com.apply_if_callable(key, self.obj)
      189         indexer = self._get_setitem_indexer(key)
  --&gt; 190         self._setitem_with_indexer(indexer, value)
      191 
      192     def _validate_key(self, key, axis):
  
  ~/anaconda3/lib/python3.7/site-packages/pandas/core/indexing.py in _setitem_with_indexer(self, indexer, value)
      640                 # setting for extensionarrays that store dicts. Need to decide
      641                 # if it's worth supporting that.
  --&gt; 642                 value = self._align_series(indexer, Series(value))
      643 
      644             elif isinstance(value, ABCDataFrame):
  
  ~/anaconda3/lib/python3.7/site-packages/pandas/core/indexing.py in _align_series(self, indexer, ser, multiindex_indexer)
      781             return ser.reindex(ax)._values
      782 
  --&gt; 783         raise ValueError('Incompatible indexer with Series')
      784 
      785     def _align_frame(self, indexer, df):
  
  ValueError: Incompatible indexer with Series
  </code></pre>