title: SSRS expression - If null value then return 0 instead of blank
body: <p>I've seen a few examples but I just can't figure it out for my case.
  My expressions sums all values from field <code>Total</code> from the dataset <code>AutoDeliveryCount</code>. I need to reference the dataset since I'm using a few <code>Total</code> fields in my report. If the stored procedure returns null, how can I have my expression return 0 instead of a blank?</p>
  
  <pre><code>=Sum(Fields!Total.Value, "AutoDeliveryCount")
  </code></pre>