External Angular JS Plugin is not working in Lithium Angular

Hi,

I want to use an external AngularJs plugin within the angular app and below the code where we tried but no luck.
Following is a code sample.
Attached plugin: angularjs-dropdown-multiselect.min.js

<script type="text/javascript" src="/html/assets/lodash.min.js"></script>
<script type="text/javascript" src="/html/assets/angularjs-dropdown-multiselect.min.js"></script>

<div id="myFirstApp" ng-app="myFirstApp" ng-controller="myFirstCtrl" class="lia-page lia-content lia-top-quilt" li-bindable>

<div id="deliveryType" ng-dropdown-multiselect="" options="deliveryType" selected-model="selectedDeliveryType" checkboxes="true" extra-settings="deliveryTypeSettings" translation-texts="deleveryTypeText" class="dropdown-multiselect-button" events=""></div>

</div>

<@liaAddScript angular="true">
;(function (angular) {
 var coreModuleDeps = LITHIUM.AngularSupport.getOptions().coreModuleDeps || [];
coreModuleDeps.push('myFirstApp');

 LITHIUM.AngularSupport.setOptions({ coreModuleDeps: coreModuleDeps });

angular.module('myFirstApp', ['angularjs-dropdown-multiselect']).controller('myFirstCtrl', ['$scope', function ($scope) {

     $scope.deliveryType = [{"id":"ILTc","label":"Live Instructor Led Training - Classroom"},{"id":"ILTv","label":"Live Instructor Led Training - Virtual"},{"id":"ODC","label":"On-Demand - Self-Paced Classroom"},{"id":"ODLe","label":"On-Demand Learning"},{"id":"ODLab","label":"On-Demand Lab"},{"id":"ODS","label":"On-Demand Subscription"}];
     $scope.selectedDeliveryType = [];
     

     $scope.deliveryTypeSettings = {
          scrollableHeight: 'auto',
          scrollable: true,
          showCheckAll: false,
          showUncheckAll: false
     };
     
$scope.deleveryTypeText = {
          checkAll: 'Check All',
          uncheckAll: 'Uncheck All',
          selectionCount: 'checked',
          selectionOf: '/',
          searchPlaceholder: 'Search...',
          buttonDefaultText: '--Select Delivery Type--',
          dynamicButtonTextSuffix: 'checked'
     };

}]);
})(LITHIUM.angular);
</@liaAddScript>

Could you please guide us to resolve this issue?

Thanks!
Kamlesh