Hello Howard,
I have checked your site and it looks like there's 2 issues here. The first issue, it seems like some other plugin or component is actually already using the same Facebook library which causes some naming conflicts (Which was why you are getting the blank pages).
The other issue seems like the application that you configured on Facebook, might not be setup correctly. Can you provide us your facebook account access so we can have a better look on your setting?
Please provide them in the form below.
Please be advise.
Thanks.