问“$(.).validate不是一个函数”，即使我直接将jquery.validate.js代码放在头上

EN

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js">         </script>
<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.15.0/jquery.validate.js"></script>
<script>
    $(document).ready(function () {
        $("#signupform").validate({
            rules:{
                email: {
                    required: true,
                    minlength: 10
                },
                password: {
                    required: true
                },
                password2: {
                    equalTo: "#password"
                }
            },
            messages: {
                email: "test"
            }
        });
    });
</script>

<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.15.0/jquery.validate.js"></script>