title: Actions on Google: Request contains an invalid argument
body: <p>I have a Google Assistant app already in production, which gives First Aid treatment procedures whenever someone is in need. I built this app with Dialogflow. It was running well for the past few months, but now whenever I call something after the app's first statement, it gives me this error:</p>
  
  <pre><code>Request contains an invalid argument. 
  The query pattern 'Where can I get `$SchemaOrg_Number:ordinal aid information?' 
  contains an undefined parameter` (name: 'ordinal' type: 'SchemaOrg_Number').
  </code></pre>
  
  <p>This error comes when I try to implement my app from Dialogflow to Google Assistant, and from the error message, it is not clear that exactly which part of the program is faulty. I have no idea where to go from here and I'd love your help. Thanks a tonne!</p>
  
  <p><a href="https://i.stack.imgur.com/XyzWw.png" rel="nofollow noreferrer">Here's my Dialogflow Screen</a></p>
  
  <p><a href="https://i.stack.imgur.com/rEA5R.png" rel="nofollow noreferrer">Here's the AoG Simulator Screen where the error happened</a></p>