title: Using a pull point subscription and PullMessages with an ONVIF camera
body: <p>I developed a video surveillance program and I need to connect to an Axis camera using the ONVIF protocol to read the events.</p>
  
  <p>When I use the <code>CreatePullPointSubscription</code> request, I get an address but I do not know how to use the parameter <code>ReferenceParameters dom0: SubscriptionId</code> in the <code>PullMessages</code> request.
  It always returns an <code>InvalidArgs</code> fault.</p>
  
  <p>How can I correctly apply the subscription ID to the <code>PullMessages</code> request?</p>