Hi, I use this plugin: jQuery.i18n.properties

I put this code:

/* Do stuff when the DOM is ready */
    jQuery(document).ready(loadMessage);

    /*
     * Add elements behaviours.
     */
    function loadMessage() {
        jQuery("#customMessage").html("test");
        jQuery.i18n.properties({
            name:'up_mail_messages',
            path:'https://static.unifiedpost.com/apps/myup/customer/upmail/upmail_messages/',
            mode:'both',
            language:'en',
            callback: function() {
                var messageKey = 'up.mail.test';
                //alert(eval(messageKey));
                jQuery('#customMessage').html(jQuery.i18n.prop(messageKey));
            }
        });
    }

I do not understand why, in the customeMessage div it prints out:

[up.mail.test]

instead of the value of it:

up.mail.test=messages loaded from en

Can anybody show me where i am wrong? I;ve spent about two hours on it without finding any clue...

Many Thanks.

Ps: here is the message file: https://static.unifiedpost.com/apps/myup/customer/upmail/upmail_messages/up_mail_messages_en.properties