Error Message after Installing Plug-In

Hi,
I installed your plugin. When checking with the facebook debugger I get the following error message:
Errors That Must Be Fixed

Object Invalid Value: Object at URL ‘http://www.thebirdschool.com/’ of type ‘website’ is invalid because the given value ” for property ‘og:image:url’ could not be parsed as type ‘url’.

I am a beginner. Could you please help and let me know, if this is because of your lugin and what I need to do to fix it?

Thanks,
Ann.

http://wordpress.org/extend/plugins/facebook-thumb-fixer/