Make sure your application handlebars template is being injected in this format
<script type="text/x-handlebars" data-template-name="application">
</script>
or
<script type="text/x-handlebars" >
</script>
Naming is super important in Ember, if your template is getting injected with a different name, like:
<script type="text/x-handlebars" data-template-name="templates/application">
</script>
Then you'd need an application view that says to use a different template name than the default template name.
Warthog.ApplicationView = Ember.View.extend({
templateName: 'templates/application'
})