Activate theme programmatically


I would like to know how I can automatically activate a theme when a new blog is created in a multisite installation.

Right now I’ve got this:

add_action('wpmu_new_blog', 'create_new_site');
function create_new_site($blog_id) {

    // Do all the work
    switch_theme('marlun', 'marlun');


My theme is located in wp-content/themes and the stylesheet is called style.css. The theme is a reworked twenty eleven. However nothing happands when a new blog is created. If I go to the apearance tab in the new blog my theme is available but not activated.

Noticed I had misspelled blog_id as blogid. Problem solved.