title: Paypal payment_gross is empty
body: <p>I am working with with paypal sandbox.</p>
  
  <p>According with <a href="http://www.bluevisionsoftware.com/WebSite/TipsAndTricksDetails.aspx?Name=PayPal" rel="noreferrer">that article</a> after IPN verification i need to check <code>payment_gross</code> field but in my case it is empty.</p>
  
  <p>Also i have fields <code>mc_gross</code> and <code>mc_gross_1</code> which is contains paid amount so should i check <code>mc_gross</code> insteard? any thoughts why <code>payment_gross</code> is empty?</p>