title: Oracle Application Express Charts
body: <p>I'm still getting "Invalid chart query" error while trying to make flash chart with APEX. 
  My query code:</p>
  
  <pre><code>select null, sum(kwota), to_char(data_zakupow,'YY-MM')
  from zakupy
  group by to_char(data_zakupow,'YY-MM')
  </code></pre>
  
  <p>When i use it as a database query I get:</p>
  
  <pre><code>NULL|SUM(KWOTA)|TO_CHAR(DATA_ZAKUPOW,'YY-MM')
  -   10  12-11
  -   4   12-03
  -   63  12-01
  </code></pre>
  
  <p>IDK why I get this error and how to fix it.</p>