title: Create a chart using the records of certain type grouped by month, with a moving balance
body: <p>I am trying to create a chart (bar or line) in crystal from one table in my database (Sage CRM).</p>
  
  <p>The records are as follows</p>
  
  <pre><code>CustomerId      Date            Invoice              Amount
  
  1234           3/4/2013        Cust Invoice           3322.00   
  1234           3/4/2013        Payment                2445.00  
  1234           4/5/2013        A/c transaction         322.00  
  1234           5/6/2013        interest                 32.00 
  1234           6/6/2013        payment                 643.00 
  </code></pre>
  
  <p>So I would like to have a report that meets the following criteria</p>
  
  <ol>
  <li>Only records for the last 12 months  grouped in month</li>
  <li>Only invoice types of payment, invoice and interest</li>
  <li>A moving balance that calculates all the invoice amounts ie</li>
  </ol>
  
  <p>(when displaying the  information for July 2012, the moving balance will be the total of all  invoices prior to this date.
  Without this field I can create the chart no problem using select expert but I am not sure now what to do)</p>
  
  <p>Should I use a cross tab? if so how will I do the selection to only show the invoices I want and the the date range I want? </p>