Getting an error message when clicking on Edit Settings for FacebookSDK

I am having an issue with getting the FacebookSDK to edit the settings in Unity. When I click on the Facebook tab and then click on Edit Settings, I get an error message.

The message is: FileNotFoundException: Could not load file or assembly ‘Facebook.Unity.Settings, Version=, Culture=neutral, PublicKeyToken=null’ or one of its dependencies.

Is there a solution to this matter to allow me to edit the facebook settings so I can add the sdk package to my game?

I have included two pictures for you to see, the Inspector and the Project to see the location of the file, Facebook.Unity.Settings.

I have found that this happens if the DLL was built with a different version of the .NET framework than what the unity player is using.

Where did you get the Facebook.dll file from? Facebook itself? or from the asset store?