title: I'm unable to plot a backtest of my algorithm
body: <p>Thank you in advance for any help!</p>
  <p>I'm trying to backtest a very simple moving average cross over strategy in Python. I'm using the Jupyter notebook.</p>
  <p>I've installed and imported backtrader and matplotlib. However, I'm unable to plot anything and I can't figure out this bug :/</p>
  <p>I'm a fairly successful trader but am new to python. Thank you for your help!</p>
  <p><a href="https://i.stack.imgur.com/gFbQO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gFbQO.png" alt="First half of my code!" /></a>
  <a href="https://i.stack.imgur.com/XnqBh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/XnqBh.png" alt="Second half of my code!" /></a></p>