jquery issue in custom module magento 2

i am on the way to create a custom module for sliding. But always its driving me crazy on jquery issues. Sometime the js will load and everything will be fine. After sometime, jquery wont get loaded.

var config = {
map: {
    '*': {
             'flexslider': 'Slidermodule_Mymodule/js/jquery.flexslider-min'
    }
} };

and the script looks like

require([ 'jquery', 'flexslider', 'domReady!'], function(){   jQuery(document).ready(function () {
jQuery('.flexslider').flexslider();  });  });

Some time there is no error. Sometime there is error on refresh. Please advise.