title: DevExpress - Xtra Reports: Group Header/Sorting can't use an Aggregate Function
body: <p>I have to use DevExpress's Xtra Reports which is in a third-part app. I have a group header that displays 'State' but grouped by 'Sum(Payment_Amount)' in descending order of the total and not the name of the state (This is a requirement.). </p>
  
  <p>Group Header:  State
  Detail: Each item in this State | Payment_Amount
  Group Footer:  Sum(Payment_Amount) for this State</p>
  
  <p>Must sort the groups by the Sum(Payment_Amount) in descending order.</p>
  
  <p>Example: if California has the greatest total amount of the payments, it is first and not Wyoming.</p>
  
  <p>How do I include the Sum(Payment_Amount) in the grouped header collection? Can't include the value of the textbox. Not allowed to put an aggregate function in the expression of a calculated field.</p>