DRUPAL: Views, exposed filter: how to unselect all items as default

I'm using Views with an exposed filter with tags. (integrated with Better exposed filter). In the settings I can select one or more tags as starting selected tags when I visit the page for the first time.

However I cannot unselec开发者_Go百科t all of them. I would like to not have selected tags at the beginning and at the same to see all articles. (N.B. I'm using "Is one of" operator, and it works perfectly for my website).

So the question is, can I have none tags unselect as default and see all my nodes ?

thanks

You must mark the filter as optional.