If your website is in localhost or in a sub-directory (not at the root of your domain or sub-domain), the rating bar can work not properly. Just edit the file named rating.js located in <your site>/components/com_alphacontent/assets/js.

Search this lines below (line 67):

var myDomain = '';

if ( document.domain!='localhost' ) {
        myDomain = /(http?:\/\/[^\/]+)/.exec(window.location.href)[1] + '/';
}

and change like this

var myDomain = 'your url/';                           // example : var myDomain = 'http://www.xxxxxxx.com/xxxxx/' or var myDomain = 'http://localhost/xxxxxx/'

do not forget the last /

and comment this fllowing lines

/*
if ( document.domain!='localhost' ) {
        myDomain = /(http?:\/\/[^\/]+)/.exec(window.location.href)[1] + '/';
}
*/