Embedded Form on Facebook: Why my form shows as not found?

Please, follow this guide that will help you to properly embed your form on your Facebook page: https://www.jotform.com/help/22-Adding-a-Form-to-Your-Facebook-Page 

Here's an example about how the form will be embedded: https://www.facebook.com/Testing-JF-1154727517939621/app/684336108254110/ 

Hope this helps.