title: Can't Sum Formula in Crystal Reports
body: <p>I am trying to sum two different formula fields in Crystal.  It will not let me select them from the Sum.  The first formula is </p>
  
  <pre><code>if Sum ({tblPostedLine.pli_QUANTITY_SHIPPED}) &gt;= 1 
  then {tblPostedLine.pli_NET_PRICE}
  else ({tblPostedLine.pli_NET_PRICE} * -1)
  </code></pre>
  
  <p>I am trying to take a price and make it a negative value if the quantity is a negative value.  I then want to sum the amounts to get a net amount that was shipped.</p>
  
  <p>The other formula is </p>
  
  <pre><code>If PreviousIsNull({RodsvwCatalogAnalysis.pro_PROMOTION_CODE}) 
  or ({RodsvwCatalogAnalysis.pro_PROMOTION_CODE}) &lt;&gt; 
  Previous({RodsvwCatalogAnalysis.pro_PROMOTION_CODE}) 
  then {RodsvwCatalogAnalysis.pit_AREA_PER_PAGE} else 0
  </code></pre>
  
  <p>With this formula, I am trying to sum at a group level, not the details level.  When I just sum the group level number, it is adding it every time the value is listed in the details as well.</p>
  
  <p>I am open to any suggestions.
  Thanks!</p>