ng-model works with ng-repeat but not with collection-repeat

Im doing the code below, and it works with ng-repeat but not with collection-repeat:

<ul collection-repeat="line in lines">
        <li class="line-item">
            <ion-radio class="line-item" ng-model="displayLine" ng-value="{{line.id_linha}}" ng-change="serverSideChange(line)" >
          <div class="line-number">{{line.numero}}</div>
          <div class="line-name">{{line.nome}}</div>
        </ion-radio>
        </li>
    </ul>
<div class="control-panel">
        <a class="button center" ng-click="drawLines(displayLine)" href="#/app/playlists">
          <span>VER NO MAPA</span>
        </a>
    </div>

im i missing something? I want it to work but i get undefined in drawLines the ng-change doesnt work, what i want is only to send the data to drawLines

controller:

$scope.serverSideChange = function(line){
    $scope.displayLine = line;
  };
$scope.drawLines = function(line){ console.log(line); }