title: Desktop-Streaming(Live Desktop & Audio Streaming to the browser with WebRTC) Error
body: <p>I wanted to load the xscreen driver. so I opened a terminal and typed the following commands:</p>
  
  <pre><code>$uv4l --driver xscreen --auto-video_nr --display :0 --framerate 10 --server-option '--port=5678'
  </code></pre>
  
  <p>This is the normal result:</p>
  
  <pre><code>raspberrypi ~ $ uv4l --driver xscreen --auto-video_nr --display :0 --framerate 10 --server-option '--port=9000'
  
  [core] Trying driver 'xscreen' from built-in drivers...
  [core] Driver 'xscreen' not found
  [core] Trying driver 'xscreen' from external plug-in's...
  [driver] Opening display: :0
  [driver] Display open, screen 0: 640x480, depth: 24, bpp: 32, big endian: false
  [driver] Specified capturing rectangle: (xorigin 0, yorigin 0, width 640, height 480)
  [core] Device detected!
  [core] Trying to load the the Streaming Server plug-in...
  [server] HTTP Streaming &amp; WebRTC Signalling Server v1.1.18 built on Apr 22 2015
  [core] Streaming Server loaded!
  [core] Cannot create /dev/video0 because file already exists
  [core] Registering device node /dev/video1
  [server] Web Streaming Server listening on port 9000
  </code></pre>
  
  <p>But I got this message: </p>
  
  <pre><code> $ uv4l --driver xscreen --auto-video_nr --display :0 --framee 10 --server-option '--port=5678'
  
  &lt;notice&gt; [core] Trying driver 'xscreen' from built-in drivers...
  &lt;warning&gt; [core] Driver 'xscreen' not found
  &lt;notice&gt; [core] Trying driver 'xscreen' from external plug-in's...
  &lt;warning&gt; [core] /usr/lib/uv4l/libxscreen.so: undefined symbol: _ZN5boost11ththread5hiden9sleep_forERK8timespec
  &lt;alert&gt; [core] No device detected
  </code></pre>
  
  <p>What is my problem?
  Help me please!</p>