Excerpt doesn't work

I’m using a Rbox theme from WP and I cannot get the excerpt field to work. When I submit a post with an excerpt, it doesn’t use the excerpt and instead features the entire post. WP doesn’t automatically crop to 55 words either.

[closed as duplicate – please continue with http://wordpress.org/support/topic/excerpt-field-doesnt-create-excerpt?replies=1 and add more information there if necessary]