ckeditor: mathJax pluggin installation is not working

Hi,
I'm developing PHP based application which need a wysiwyg form in it. so i decided to use ckeditor. I've done with the original installation, it working properly. But i need to add mathJax pluggin, the installation is not working. Not only the mathJax icon (sygma) not appear, even all the menu of ckeditor disappear.

What i've done is:
1. extract the mathJax folder and put it in pluggin folder

2. I've made some editing in config.js to run the mathJax, as shown below

CKEDITOR.editorConfig = function( config ) {
    // Define changes to default configuration here. For example:
    // config.language = 'fr';
    // config.uiColor = '#AADC6E';
    config.mathJaxClass = 'my-math';
    config.extraPlugins = 'mathjax';
    config.mathJaxLib = 'http://cdn.mathjax.org/mathjax/2.6-latest/MathJax.js?config=TeX-AMS_HTML';
};

Code (JavaScript):

The CKeditor documentation says that since version 4.x, the mathJax library should be defined manually with the full path. I did it like the last line above.

Please help me to solve this problem

Thank You