This usually happens with newly created Facebook pages which wasn’t authorised when you last performed an authorization setup. You will simply need to authorize your MyCart to use your new Facebook page.
You will simply have to authorize MyCart to use your new Facebook page by following the steps below:
1. On the “Connect to Facebook” tab, click “Reauthorize”
2. You will be directed to Facebook for authorization, and you must choose to "Edit Settings"
3. You can select all the Facebook pages you want to your MyCart connect and customize your authorization settings accordingly.
Note: If a Facebook page that currently connected to another MyCart shop is not checked, the MyCart shop of that page will stop working
4. Complete the authorization
5. At this point, you will be re-directed to MyCart and will see the Facebook pages that you have just connected your MyCart to.