Angularjs 无法使用by.repeater中的元素单击复选框

由于某些原因，我无法单击带有

by.repeater

的复选框。没有错误。查看浏览器时，复选框根本没有被选中。有什么想法吗？如果可能的话，我想继续使用.repeater的

by

  this.modelChoices = function(rowNumber) {
    return element.all(by.repeater('model in vehicleCheckboxes.models'));
  } 

  checkboxes.modelChoices().get(0).click();

鉴于：

<div>
    <div class="input-group" ng-repeat="item in vm.dataFiles | filter:vm.query">
        <span class="input-group-addon">
            <input type="checkbox" ng-model="item.isChecked">
        </span>
        <label class="form-control">{{item.name}}</label>
    </div>
</div>

it("should disable the create button when there are no checked items in the vm.dataFiles", function () {
    var dataFiles = element.all(by.repeater("item in vm.dataFiles"));
    var firstCheckbox = dataFiles.get(0).element(by.model("item.isChecked"));
    var btnCreate = element(by.id("btnCreate"));

    expect(btnCreate.isEnabled()).not.toBeTruthy();
    firstCheckbox.click();
    expect(btnCreate.isEnabled()).toBeTruthy();
    firstCheckbox.click();
    expect(btnCreate.isEnabled()).not.toBeTruthy();
});