title: ngTable can't generate header
body: <p>I'm using ngTable with this code:</p>
  
  <p>HTML:</p>
  
  <pre><code> &lt;table data-ng-table="tableParams" class="table table-condensed table-bordered table-striped"&gt;
                          &lt;tbody&gt;
                              &lt;tr data-ng-repeat="task in $data"&gt;
                                  &lt;td data-title="''"&gt;
                                      &lt;input type="checkbox" style="display: block; margin: auto;" ng-model="task.IsSelected" ng-change="optionToggled()"&gt;
                                  &lt;/td&gt;
                                  &lt;td data-title="''" style="text-align: center"&gt;
                                      &lt;i class="glyphicon glyphicon-flag" ng-show="task.IsToday"&gt;&lt;/i&gt;
                                      &lt;i class="glyphicon glyphicon-ok" ng-show="task.IsCompleted"&gt;&lt;/i&gt;
                                  &lt;/td&gt;
                                  &lt;td data-title="'Subject'" data-sortable="'Subject'"&gt;{{task.Subject}}&lt;/td&gt;
                                  &lt;td data-title="'Priority'" data-sortable="'PriorityValue'"&gt;{{task.PriorityValue}}&lt;/td&gt;
                                  &lt;td data-title="'Status'" data-sortable="'StatusValue'"&gt;{{task.StatusValue}}&lt;/td&gt;
                                  &lt;td data-title="'Due Date'" data-sortable="'DueDate'"&gt;{{task.DueDate}}&lt;/td&gt;
                                  &lt;td data-title="'Completed'" data-sortable="'CompletedValue'"&gt;{{task.CompletedValue}}&lt;/td&gt;
                                  &lt;td data-title="'Date Completed'" data-sortable="'DateCompleted'"&gt;{{task.DateCompleted}}&lt;/td&gt;
                                  &lt;td data-title="'Action'"&gt;
                                      &lt;button type="button" style="display: block; margin: auto;" class="btn btn-info btn-xs" ng-click="editRow(task)"&gt;
                                          &lt;i class="glyphicon glyphicon-edit"&gt;&lt;/i&gt;
                                      &lt;/button&gt;
                                  &lt;/td&gt;
                              &lt;/tr&gt;
                          &lt;/tbody&gt;
                      &lt;/table&gt;
  </code></pre>
  
  <p>Javascript:</p>
  
  <pre><code> $scope.tableData = [];
  
      $scope.tableParams = new ngTableParams({
          page: 1, // show first page
          count: 10, // count per page
          sorting: { DueDate: "asc" } // initial sort order,
      },
      {
          paginationMaxBlocks: 10,
          paginationMinBlocks: 2,
  
          getData: function($defer, params) {
  
              var sorting = params.sorting();
              var keySorting = Object.keys(sorting)[0];
              var valueSorting = sorting[keySorting];
  
              var count = params.count();
              var pageIndex = params.page() - 1;
              var keySearch = angular.isDefined($scope.textSearch) ? $scope.textSearch : '';
  
              taskService.pagingTasks(pageIndex * count, count, keySearch, keySorting, valueSorting).then(function(data) {
                  var obj = angular.fromJson(data);
                  params.total(obj.Total);
  
                  formatToDateTime(obj.Data);
  
                  $scope.tableData = obj.Data;
                  $defer.resolve(obj.Data);
              });
          }
      });
  </code></pre>
  
  <p>But when I run my website I see ngTable generate </p>
  
  <p><a href="https://i.stack.imgur.com/9M1Dr.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9M1Dr.png" alt="enter image description here"></a></p>
  
  <p>And my browser console show this error:</p>
  
  <p><a href="https://i.stack.imgur.com/IS69F.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/IS69F.png" alt="enter image description here"></a></p>
  
  <p>I have no idea why ngTable can't generate columns header.
  Currently, I must create columns header by manually.</p>