If the OK button is not pressed, then some action required for correct publication of the post has not been performed.
Please check it out:
- have you selected a page to be published in the post planning window?
- If you have an account connection, please see the Accounts section.
- whether you have exceeded the limit for characters in the text (the limits are indicated under the text field)
- have you attached a photo or video, if it's a post for Instagram.