Q:

Facebook widget working for some url but not for others

Take a look at this fiddle: JsFiddle
As you can see I have put up the facebook like box with url http://facebook.com/ElizaDoolittle
The problem is that it doesnt work with all urls, try replacing the url with this url: http://www.facebook.com/fatme.safa.3?ref=fs
you will see an error notification. Why is that?? What makes the difference in url?

A:

As you can see I have put up the facebook like box with url http://facebook.com/ElizaDoolittle

That is the address of a Facebook page for a musician.

The problem is that it doesnt work with all urls, try replacing the url with this url: http://www.facebook.com/fatme.safa.3?ref=fs

That is the address of a user profile.

you will see an error notification. Why is that?

Because only pages can be liked, user profiles can not be liked. And since, the Like box also does not work for user profiles.

