Facebook Api Error 100 - Invalid Link

I am using the Facebook API to create a Send Dialog in my Rails App. I just use the format that Facebook recommends in a Javascript (as a script in HTML). My problem is that I get

Solution 1:

The image URL of http://fb-logo-75.png is not valid

It must be an absolute url (example: http://domain.com/path/to/image.png) and cannot be located on Facebook's CDN. So change that to http://your_domain.com/path/to/fb-logo-75.png