This error means that you are logged into the wrong personal profile at www.facebook.com.
When connecting a Facebook page, your PromoRepublic account syncs with a personal profile, that has an Admin role on this page. When the page is added, its Admin Facebook profile is automatically attached to your PromoRepublic account as a host. Thus, your PromoRepublic account has a specific Facebook profile associated.
In order to ensure the posting, such a personal profile must be authorized in the same browser at www.facebook.com.
In case you don't know what Facebook profile is the host on your PromoRepublic account, check it in the settings. Click on the top right corner, select Settings, and scroll down to the bottom. There you'll see the profile name.
If this is a wrong profile and you want to connect to a different one, hit on the red Disconnect Facebook button and log out. Then go to www.facebook.com, authorize in the necessary profile, get back to PromoRepublic, and re-try posting.
In case this doesn't help, please email us at [email protected].