title: Error "A number or currency amount is required here" in Formual editor of crystal reports
body: <p>i am implementing a formula in a crystal report by multiplying two columns quantity and unit price and both are of decimal type but when the query return some value it gives no exception and when query returns no value then it give exception like A number or currency amount is required here. <br>
  The formula is <br></p>
  
  <pre><code>if isNULL({dtDealerStockReport.Qty})=True or isNULL({dtDealerStockReport.UnitPrice})=true
       then
          0
       else
  
       {dtDealerStockReport.Qty}*CDBL({dtDealerStockReport.UnitPrice})
  </code></pre>