Load one template into a another one in Ember.js

Within one of my route's renderTemplate method, I've tried to render a different template by using this.render:

App.IndexRoute = Ember.Route.extend({

    renderTemplate: function() {

        this.render( 'dashboard', {
            into: 'admin'
        });

    }

});

But the application within the browser is empty and the console shows the following:

Assertion Failed: You attempted to render into 'admin' but it was not found

After this error message, I thought that the "admin" template might simply not be existent, but it it's there. Both the "dashboard" and the "admin" template are loaded. And the weirdest thing: I'm able to use this.render( 'dashboard' ) and this.render( 'admin' ) and both of them work fine.

What am I doing wrong? I've even added an {{outlet}} tag to the "admin" template.