plugins - Asset Compress Plugin not creating cached files with cakephp 2.x

Question

I am trying to compress js files using asset compression cakephp plugin.. But it is not creating files to webroot/cache_js folder.. What is wrong ? Can you explain ? Here is my asset_compress.ini code

[General]
cacheConfig = true

[js]
paths[] = WEBROOT/js/
cachePath = WEBROOT/cache_js/

[custom.js]
files[] = jquery.js
files[] = jquery-ui.js

In my bootstrap.php I loaded

CakePlugin::load('AssetCompress', array('bootstrap' => true));

Debug level is set to 2.. With debug level 0 also, file is not created

Thank you..