title: Sumo and Traci : LastStepVehicleNumber does not update
body: <p>I am using Sumo 0.27.1 and the Traci interface.</p>
  
  <p>I am trying to get the number of vehicles occupying a lane and for that 
  I use the following java code :</p>
  
  <pre><code>     Repository&lt;Lane&gt; lanes = conn.getLaneRepository();
       Map&lt;String, Lane&gt; laneMap = lanes.getAll();
       Iterator&lt;Entry&lt;String, Lane&gt;&gt; laneMapIterator = laneMap.entrySet().iterator();
  
       while(laneMapIterator.hasNext())
       {
           Entry&lt;String, Lane&gt; laneElem = laneMapIterator.next();
           Lane l = laneElem.getValue();
  
           if (!l.getID().startsWith(":"))
           {
               System.out.println("Lane ID: "+ l.getID() + " CO2: " + l.getCo2Emission());
               System.out.println("Lane ID: "+ l.getID() 
  + " Occupancy: " + l.getLastStepOccupancy() + " Vehicle Number: " 
  + l.getLastStepVehicleNumber());
           }
       }
  </code></pre>
  
  <p>Although there are many cars introduced in the simulation, I can the 
  CO2, occupancy and vehicle number for just 3 of the lanes; and I get the 
  same numbers during the simulation.</p>
  
  <p>A similar code is working fine for getting individual vehicle meters, 
  but does not work for lanes.</p>
  
  <p>I there any update or reset command that I should explicitly take care of ?</p>
  
  <p>Thanks in advance,</p>
  
  <p>Vlad</p>