$(function() {
    $('form').validate({ submitHandler: function(form) {
        CheckCaptcha(form);
    }
    });
});

function NewCaptcha() {
    $('#captchapic').attr('src', 'captcha.aspx?rnd=' + Math.random() * 900);
    return false;
}

function CheckCaptcha(form) {
	if($('#fldcaptcha').val()==null) 
	{	
        form.submit();
		return false;
	}
    $.get('captcha.aspx?check=' + $('#fldcaptcha').val(), function(check) {
        if (check == "ok") {
        $('#SubmitDemo').attr('disabled', true);
        form.submit();
        }
        else {
            $('#captchapic').attr('src', 'captcha.aspx?rnd=' + Math.random() * 900);
            $('#error').show();
        }
    });
    return false;
}