Scope issue in AngularJS using AngularUI Bootstrap Modal

Looks like a scope issue. I got it to work like this:

var ModalInstanceCtrl = function ($scope, $modalInstance) {
    $scope.input = {};
    $scope.ok = function () {
        alert($scope.input.abc);
    };

    $scope.cancel = function () {
        $modalInstance.dismiss('cancel');
    };
};

HTML:

<textarea ng-model="input.abc"></textarea>