statsmodels, time series predict out-of-sample error
<p>My data:</p>

<pre><code>ipdb&gt; dta
             plays
2015-03-01   401.0
2015-03-02   350.0
2015-03-03   448.0
2015-03-04   490.0
...            ...
2015-08-23   655.0
2015-08-24   731.0
2015-08-25   684.0
2015-08-26   774.0
2015-08-27   808.0
2015-08-28   732.0
2015-08-29   694.0
2015-08-30   798.0
</code></pre>

<p>The data starts from 2015-03-01 to 2015-08-30, and I want to predict the future values.</p>

<p>My code snippt</p>

<pre><code>arma_mod30 = sm.tsa.ARMA(dta, (d_level, 0)).fit()
result = arma_mod30.predict('2015-09-01', '2015-10-30', dynamic=True)
</code></pre>

<p>But the predict fuction returned the fllowing error:</p>

<pre><code>ValueError: date 2015-09-01 00:00:00 not in date index. Try giving a date that is in the dates index or use an integer
</code></pre>

<p>How to predict future dates that not in the date index? Thanks!</p>