CoSchedule was unable to read posts from your blog. This usually happens if you do not have any, or enough, existing blog posts to be sync to CoSchedule.
To correct the issue, you can create at least 2 posts on your blog. They can even be in a draft status. Once the posts are created, you can Refresh Your WordPress Connection. It may take a few moments as CoSchedule connects and syncs your posts and settings from WordPress.