title: how to stop Subscribe?
body: <p>I have two selects where the seconds values depends on the choosen value in the first one (Countrys / States) both are collections</p>
  
  <p>When i subscribe with for example Belgian as country i get the states for Belgian
  But when i choose another country (ex. Netherlands) the states are added !</p>
  
  <p>I read that i must stop de subscription with .stop() an renew the subscription but this doesnt deems to work ???</p>
  
  <p>My code : </p>
  
  <pre><code> 'click #stateList' : function(event, template) {
      var x = myTrim($("#countryList").val());
      var y = Countrys.findOne({country: x});
      var z = y.nr;
      if(this.stateSub != null){
          this.stateSub.stop();
      }
      this.stateSub = Meteor.subscribe('stateList', z);
  
  }
  </code></pre>
  
  <p>It seems that this.stateSub is always undefined even if there is already a working subscribe ???</p>
  
  <p>What am i doing wrong ???</p>
  
  <p>thanks</p>