On page load there is no issues with AddThis widget. But when the 'Share' button is binding via ajax, then the AddThis functionality will not work. To fix this solution, use the following script.

<script type="text/javascript">
    function generateAddThisButton(ID,URL,Title,Description) {
        var addthis_ui_config =
        {
            services_compact: 'facebook, myspace, igoogle, netvibes, windows, dashboard, more'
        }
        var host = window.location.host;
        var propertyURL = host + URL;
        var propertyTitle = Title;
        var propertyDescription = Description.replace('<p>','').replace('</p>','');
        var addthis_share_config =
        {
            url: propertyURL,
            title: propertyTitle,
            description: propertyDescription
            //swfurl: "http://www.youtube.com/v/1F7DKyFt5pY&hl=en&fs=1",
            //screenshot: "http://i2.ytimg.com/vi/1F7DKyFt5pY/default.jpg"
        }
        addthis.button("#" + ID, addthis_ui_config, addthis_share_config);
    }
</script>