title: Why Amazon Forecast cannot train the predictor?
body: <p>While training my predictor I came across this error and I got stuck how to fix it.</p>
  
  <p>I have two data-series, a "Target time-series data" with 9234 rows and a single "item_id" and a second one that is "Related time-series data" with the same number of rows as I only have a single id.</p>
  
  <p>I'm setting de data with a window of 180 days, what is exactly the difference between the second and the first number that has appeared on the error, 9414 - 9234 = 180.</p>
  
  <pre><code>We were unable to train your predictor.
  Please ensure there are no missing values for any items in the related time series, All items need data until 2020-03-15 00:00:00.0. For example, following items have missing data: item: brl only has 9234/9414 required datapoints starting 1994-06-07 00:00:00.0, please refer to documentation for additional details.
  </code></pre>
  
  <p>Once my data don't have missing data and it's on a daily basis why is it returning this error?
  My data starts on 1994-06-07 and ends on 2019-09-17. Why should I have 9414 data points rather than 9234? 
  Should I take out 180 days in my "Target time-series data"?</p>