在预构建嵌套模型实例时，Rails nested_form link_to_add不起作用

I'm having a rough go integrating ryanb's awesome nested_form gem into my rails 3.1.3 application. I'm afraid my Javascript skills are too limited to know whether it's my code (likely) or the gem that needs changed. Maybe someone here can help.I'm having a rough go integrating ryanb's aweso