Unable to display facebox with custom content

Unable to display facebox with custom content

In my html file, I have a javascript function,
$("#contactopts").change(function() {
var response = simplefunc();
$('#sampID').html(response);
$.facebox($('#sampID'));
}
The function simplefunc is a jquery function that returns a html file as a
response from the backend.
I am expecting a facebox with the content of the html file which is sent
from the backend. But instead I'm getting an empty facebox. And I tried
console.log(response. Firebird says response is undefined..
Could someone please tell me what I'm doing wrong? I can see that I'm
missing something fundamental..