title: Problems with Listpicker App Inventor
body: <p>I'm a beginner at App Inventor and I don't know what I'm doing wrong with the <code>listpicker</code>.
  I am trying to create and app to reproduce the music I have stored in my server but when i display the <code>listpicker</code> I can't click any of the options and also I can't go back to the first screen. Here I put my code:</p>
  
  <p>Image 1
  <img src="https://i.stack.imgur.com/4KbST.png" alt="enter image description here">
  Image 2
  <img src="https://i.stack.imgur.com/TZVOL.png" alt="enter image description here"></p>
  
  <p>I tried to remove the line that says <code>call listpicker.open</code> but it only made appear a totally black screen.
  The result of the code I just posted is exactly what I spect a list with the name and the link of the 2 songs I already upload to my server but when I click them it didn't do anything.</p>
  
  <p>Thanks for your help.</p>