Scope issue in AngularJS usando AngularUI Bootstrap Modal

plunker: http://plnkr.co/edit/wURNg8ByPYbEuQSL4xwg

example.js:

angular.module('plunker', ['ui.bootstrap']); var ModalDemoCtrl = function ($scope, $modal) { $scope.open = function () { var modalInstance = $modal.open({ templateUrl: 'modal.html', controller: 'ModalInstanceCtrl' }); }; }; var ModalInstanceCtrl = function ($scope, $modalInstance) { $scope.ok = function () { alert($scope.text); }; $scope.cancel = function () { $modalInstance.dismiss('cancel'); }; }; 

index.html:

          
Selection from a modal: {{ selected }}

modal.html:

    

Perché non riesco a ottenere $ scope.text definito in ModalInstanceCtrl, anche se posso usare $ scope.ok e $ scope.cancel?