There are four things you might check:
1) Remove the 'active' class from the last div in your markup since it makes its content visible.
2) You need to initialize the accordion via
$('.ui.accordion').accordion();
See the usage information on the Semantic UI accordion page: http://semantic-ui.com/modules/accordion.html#/usage
3) You will also need to include the Semantic UI javascript files.
4) Since you said you use the accordion in a template, you have to wrap the initializtion inside a script inside the template or (the angular way) write a short directive which will invoke the accordion initialization on the element for you.