title: Can't Access XML form Main Activity in Android Studio
body: <p>I cannot access the elements in my XML form the main activity,
  writing the element id throws errors as if the element is not even there.
  Basically Main can't see what is written in XML file, even though they are linked.</p>
  <p><a href="https://i.stack.imgur.com/jKWjm.png" rel="nofollow noreferrer">Can't detect the getBmiButton button from XML</a></p>
  <p><a href="https://i.stack.imgur.com/8Yko2.png" rel="nofollow noreferrer">Button was defined here</a></p>