title: TypeError: int() argument must be a string, a bytes-like object or a number, not 'Timestamp'
body: <p>I am running a time series model and in order ot get the predictions I get the error</p>
  
  <blockquote>
    <p>TypeError: int() argument must be a string, a bytes-like object or a number, not 'Timestamp'</p>
  </blockquote>
  
  <p>Input Code: </p>
  
  <pre><code>pred = results.get_prediction(start=pd.to_datetime("2018-09-01"), dynamic=False)
  </code></pre>
  
  <p>Output:</p>
  
  <pre><code>---------------------------------------------------------------------------
  TypeError                                 Traceback (most recent call last)
  &lt;ipython-input-41-f3c669d7c5dd&gt; in &lt;module&gt;()
  ----&gt; 1 pred = results.get_prediction(start=pd.to_datetime("2018-09-01"), dynamic=False)
  
  /anaconda3/lib/python3.6/site-packages/statsmodels/tsa/statespace/sarimax.py in get_prediction(self, start, end, dynamic, index, exog, **kwargs)
     1924         # Handle start, end, dynamic
     1925         _start, _end, _out_of_sample, prediction_index = (
  -&gt; 1926             self.model._get_prediction_index(start, end, index, silent=True))
     1927 
     1928         # Handle exogenous parameters
  
  /anaconda3/lib/python3.6/site-packages/statsmodels/tsa/base/tsa_model.py in _get_prediction_index(self, start, end, index, silent)
      475         # indexes.
      476         try:
  --&gt; 477             start, start_index, start_oos = self._get_index_label_loc(start)
      478         except KeyError:
      479             raise KeyError('The `start` argument could not be matched to a'
  
  /anaconda3/lib/python3.6/site-packages/statsmodels/tsa/base/tsa_model.py in _get_index_label_loc(self, key, base_index)
      410         try:
      411             loc, index, index_was_expanded = (
  --&gt; 412                 self._get_index_loc(key, base_index))
      413         except KeyError as e:
      414             try:
  
  /anaconda3/lib/python3.6/site-packages/statsmodels/tsa/base/tsa_model.py in _get_index_loc(self, key, base_index)
      351             # RangeIndex)
      352             try:
  --&gt; 353                 index[key]
      354             # We want to raise a KeyError in this case, to keep the exception
      355             # consistent across index types.
  
  /anaconda3/lib/python3.6/site-packages/pandas/core/indexes/range.py in __getitem__(self, key)
      496 
      497         if is_scalar(key):
  --&gt; 498             n = int(key)
      499             if n != key:
      500                 return super_getitem(key)
  
  TypeError: int() argument must be a string, a bytes-like object or a number, not 'Timestamp'
  </code></pre>
  
  <p>But when I run this on dummy dataset it works fine but on to my dataset. I do not know where the issue is. </p>