error when clicking on placemark

Element.update("modal_container", "\u003Cdiv id=\"modal-window-template\" class=\"window\"\u003E\n \u003Cdiv class=\"corner tl\"\u003E\u003C/div\u003E\n \u003Cdiv class=\"corner tr\"\u003E\u003C/div\u003E\n \u003Cdiv class=\"content\"\u003E\n \u003Cdiv style=\"margin: 30px 0; text-align: center;\"\u003E\n \u003Cp\u003E\u003Cstrong\u003EChecking in...\u003C/strong\u003E\u003C/p\u003E\n \u003Cimg alt=\"Ajax-loading\" src=\"/images/ajax-loading.gif?1211932311\" /\u003E\n \u003C/div\u003E\n \u003C/div\u003E\n \u003Cdiv class=\"corner bl\"\u003E\u003C/div\u003E\n \u003Cdiv class=\"corner br\"\u003E\u003C/div\u003E\n\u003C/div\u003E\u003Cscript type=\"text/javascript\"\u003E\n var f = document.createElement('form')\n f.style.display = 'none'\n $('modal-window-template').parentNode.appendChild(f)\n f.method = 'POST'\n f.action = '/places/c406938b3b724cf286378b311259814316f7a14a/checkins'\n f.submit()\n\u003C/script\u003E");
Control.Modal.center($('modal_container'));