AngularJS : angular-ui-router state.go fails

on an Ionic-angular application, I'm calling:

   $state.go("main.crudlist");

and having the following exception in response:

Error: Could not resolve 'entry' from state 'main'
    at Object.transitionTo (angular-ui-router.min.js:3074)
    at Object.go (angular-ui-router.min.js:3007)
    at angular-ui-router.min.js:4057
    at angular.min.js:138
    at e (angular.min.js:40)
    at angular.min.js:44

What's that entry supposed to mean?

Here's the state declaration:

$stateProvider .state('login', { url: '/login', templateUrl: 'Content/Mobile/templates/login.html', controller: 'LoginController' })

    .state('settings', {
        url: '/settings',
        templateUrl: 'Content/Mobile/templates/settings.html',
        controller: 'SettingsController'
    })

    // setup an abstract state for the tabs directive
      .state('main', {
          url: "/main",
          templateUrl: "Content/Mobile/templates/main.html",
          abstract: true,
          controller: 'MainController'
      })


    .state('main.home', {
        url: '/home',
        views: {
            'main': {
                templateUrl: 'Content/Mobile/templates/home.html',
                controller: 'HomeController'
            }
        }
    })


   .state('main.settings', {
       url: '/settings',
       views: {
           'main': {
               templateUrl: 'Content/Mobile/templates/settings.html',
               controller: 'SettingsController'
           }
       }
   })

.state('main.crudlist', {
    url: "/crudlist",
    views: {
        'main': {
            templateUrl: "Content/Mobile/templates/crudlist.html",
            controller: 'CrudListController'
        }
    }
})