Angularjs 为什么在向应用程序添加筛选器时出错？

我的Angular应用程序有如下代码来添加服务：

stApp.factory('entityService', ['$http', '$q', '$resource', function (
                          $http, $q, $resource) {

现在我刚刚添加了一个过滤器，如下所示：

stApp.filter('truncate', function () {
    return function (value, wordwise, max, tail) {
        if (!value) return '';

调试时，我发现它在stApp.filter行中读取

但是，当我运行代码时：

{{modal.data.text | trunacate:true:15:' ...'}}

我收到一条信息说：

Error: Unknown provider: trunacateFilterProvider <- trunacateFilter
at Error (<anonymous>)
at http://127.0.0.1:81/Scripts/angular.js:2714:19
at Object.getService [as get] (http://127.0.0.1:81/Scripts/angular.js:2840:39)
at http://127.0.0.1:81/Scripts/angular.js:2719:45
at Object.getService [as get] (http://127.0.0.1:81/Scripts/angular.js:2840:39)
at $get (http://127.0.0.1:81/Scripts/angular.js:10451:24)
at filter (http://127.0.0.1:81/Scripts/angular.js:6590:14)
at _filterChain (http://127.0.0.1:81/Scripts/angular.js:6581:41)
at statements (http://127.0.0.1:81/Scripts/angular.js:6557:25)
at parser (http://127.0.0.1:81/Scripts/angular.js:6484:13) 

错误：未知提供程序：trunacateFilterProvider拼写错误

{{modal.data.text | trunacate:true:15:' ...'}}

应该是

{{modal.data.text | truncate:true:15:' ...'}}

拼写错误

{{modal.data.text | trunacate:true:15:' ...'}}

应该是

{{modal.data.text | truncate:true:15:' ...'}}

这里有输入错误：
trunacate
这里有输入错误：
trunacate