facebook thumbnail not showing when sharing url

[eluser]Unknown[/eluser]
so, we are making a new site and our 1st page for the sign up process does not post the proper thumbnail on facebook when we post the url on the status update. at first 3 of the 4 images showed but the logo did not (logo being the 5th image). after we follow the instructions online, we get only the description of the site to show that we added in the meta elements and no images at all. Is this a codeigniter issue?

I think that the router code is interfering with the thumbnails! Any thoughts?

we have looked and found instructions on facebook, http://developers.facebook.com/docs/share and on Ehow, http://www.ehow.com/how_4938148_thumbnai...share.html