Ok im logged out of facebook. All cookies cleared.
Here are the 3 steps as to what happens for me
1) I click the 'Login with facebook' button on this page
demo.sourcecoast.com/
A pop box appears to enter my facebook email and pass:
2) I enter the correct facebook details (email and pw) click login and the box disappears and message comes up "You are now being logged in using your facebook credentials"
3) Then the page in my first post above appears to say "Please enter your name".
I am sure youre right and it must be something to do with it being a business facebook account rather than personal