title: vala: Gst namespace could not be found
body: <p>I have some problems with "vala", when using gstreamer namespace "Gst"
  vala cannot recognise it...can somebody help me please?</p>
  
  <p>Error: <code>Gst namaspace could not be found</code></p>
  
  <p>I'm new to vala so I don't know what to do to resolve it</p>