My jQuery for html/php form is giving me an error

Question

Within the console I am getting an error saying that $(..).validate({ is not a function, but its working on another page? am I missing something or doing something wrong o.0? Anyone who could help much appreciated.

the jQuery script:

$(function() {
    $("#Message").validate({
        rules: {
            Name: {
                required: true,
                minlength: 2,
                maxlength: 15
                },
            Email: {
                required: true,
                email: true
                },
            Message: {
                required: true,
                minlength: 10
                 }
    }});

});