title: Chart shows NULL data (using parameter)
body: <p>I'm doing a cumulative line chart which compares some expenses between the current and the prior year. I did a parameter called &quot;Select Fiscal Period&quot;, It allows users to see the cumulative expenses in a given month. My problem is that the line chart shows the NULL values (see image bellow (blue line chart)) and the thing I need is like the image con line chart with lines yellow and green (image below).</p>
  <p><a href="https://i.stack.imgur.com/Pyyzg.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Pyyzg.png" alt="enter image description here" /></a></p>
  <p><a href="https://i.stack.imgur.com/c6Imf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/c6Imf.png" alt="enter image description here" /></a></p>
  <p>Somebody knows howto do it?</p>
  <p>Thank you very much.</p>